Random Snippets » javascript function

How to loop through checkboxes or radio button groups via JavaScript

Knix — Fri, 16 May 2008 05:00:18 +0000

Do you have a form with checkboxes or radio buttons that you would like to loop through via JavaScript? This JavaScript function will do just that!

Demo

Here is the plain HTML:

As usual, there is not too much action going on here. It is just a plain form with some checkboxes and 2 radio button groups called candy and drink. Radio buttons with the same name will be grouped and allows the users to only select one option out of the entire group. The submit button will launch the loopForm JavaScript function and the myForm DOM object is passed over as an argument. There are also 2 divs in lines 23-24 where are checkbox and radio button results will be posted. Now, on to more exciting things.

Here is the JavaScript code:

function loopForm(form) {
    var cbResults = 'Checkboxes: ';
    var radioResults = 'Radio buttons: ';
    for (var i = 0; i < form.elements.length; i++ ) {
        if (form.elements[i].type == 'checkbox') {
            if (form.elements[i].checked == true) {
                cbResults += form.elements[i].value + ' ';
            }
        }
        if (form.elements[i].type == 'radio') {
            if (form.elements[i].checked == true) {
                radioResults += form.elements[i].value + ' ';
            }
        }
    }
    document.getElementById("cbResults").innerHTML = cbResults;
    document.getElementById("radioResults").innerHTML = radioResults;
}

This function loops through all the elements in the form that was passed over to the function.

If the element is of checkbox type and it is checked, the value of this element will be appended to our cbResults variable which is keeping track of our checkbox results.

If the element is of radio type and it is checked, the value of this element will be appended to our radioResults variable which is keeping track of our radio button results.

After all the looping is finished, the results are cbResults and radioResults are inserted into the cbResults div and radioResults div respectively.

How to dynamically add content to a div and store the content to a cookie via JavaScript

Knix — Tue, 15 Apr 2008 06:45:17 +0000

This is an example of adding dynamic content via JavaScript by allowing the user type in the actual content.

Demo

Your content will be added dynamically below:

Here is the plain HTML for the demo:


Content to be added:
Type here...<h1>tags work as well</h1><u>woohoo</u>





Your content will be added dynamically below:

There are 3 important parts to the HTML code:

textarea – This is the content that the user enters. HTML tags are naturally supported.
Add content button – This buttons calls our addContent() function which passes the div id of where the content is to be entered and the actual content itself from the textarea.
myDiv – This is the id of blank div where the content will be inserted.

Here is the JavaScript code for the addContent() function:

1
2
3

function addContent(divName, content) {
     document.getElementById(divName).innerHTML = content;
}

That’s it! All it does it retrieve the DOM element, which in this case, is just an empty div and sets the innerHTML attribute to the content that is passed over to this function from the form.

This demo is in response to a request that saves the content that the user has entered.

Demo

Your name will be saved below:

Here is the HTML code:


Enter your name below and click the button.  Your name will be saved to a cookie that expires in 7 days.  When you refresh the page or come back to visit you will see a heartwarming message welcoming you back.









Your name will be saved below:

The onClick event listener will launch 2 scripts this time:

addContent – This will do exactly what it did before in the first demo and just insert the input text value inside the div.
setCookie – This will save a cookie with the name content and assign whatever is inside the input text as the value. In addition, the cookie is set to expire in 7 days.

To avoid reinventing the wheel, I have borrowed the JavaScript get and set cookie functions from W3 Schools and edited it slightly for the needs of this demo.

Here are the new JavaScript functions for cookie management:

function setCookie(c_name,value,expiredays) {
    var exdate=new Date();
    exdate.setDate(exdate.getDate()+expiredays);
    document.cookie=c_name+ "=" +escape(value)+((expiredays==null) ? "" : ";expires="+exdate.toGMTString());
}
function getCookie(c_name) {
    if (document.cookie.length>0) {
        c_start=document.cookie.indexOf(c_name + "=");
        if (c_start!=-1) { 
            c_start=c_start + c_name.length+1; 
            c_end=document.cookie.indexOf(";",c_start);
            if (c_end==-1) c_end=document.cookie.length;
            var cookieContent = "Welcome back " + unescape(document.cookie.substring(c_start,c_end));
            document.getElementById('myDiv2').innerHTML = cookieContent;
        } 
    }
}
getCookie('content');

Please refer to W3 Schools for a detailed description of these JavaScript functions. The only edit I have made is with the getCookie function in lines 13-14 where it retrieves the cookie value and inserts the content into a div. Also, line 18 is very important as it calls the getCookie function and looks for the content cookie. If the cookie exists, the content will be displayed in the myDiv2 div.

When using these JavaScripts, make sure you load them after all your HTML is loaded. Otherwise, the function would have no place to insert the cookie content.

Although using cookies is a great way to store information, there are a couple of caveats:

Size limitation – This depends on the browser but keeping your cookies to a maximum size of 4000 bytes will keep you in the safe zone.
Cookie limit per domain – This also depends on the browser but the general rule is 20 cookies per domain.

How to validate email format via JavaScript

Knix — Wed, 02 Apr 2008 05:30:08 +0000

This JavaScript demo verifies that an email address is in the correct format and that the user has typed in the same address in both fields to prevent mistyping of the address. I have borrowed the regex for verifying the correct email format from a different site.

Demo

Here is the plain HTML of the form. Please note that I have removed the action attribute because this is only a demo and we are only concerned with the client-side verification of the JavaScript function.


Email: 

Please type in your email again:

Nothing exciting here except in line 6 where the onClick event is triggered when the user clicks on the button. This event will launch the verifyEmail() JavaScript function which will check the user input of the email address.

Here is the code for the verifyEmail() function:

function verifyEmail(){
var status = false;     
var emailRegEx = /^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/i;
     if (document.myform.email1.value.search(emailRegEx) == -1) {
          alert("Please enter a valid email address.");
     }
     else if (document.myform.email1.value != document.myform.email2.value) {
          alert("Email addresses do not match.  Please retype them to make sure they are the same.");
     }
     else {
          alert("Woohoo!  The email address is in the correct format and they are the same.");
          status = true;
     }
     return status;
}

This function will return a false value if the user does not type in an email address in the correct format or if the user fails to type in the same email address in both fields. If the email addresses passes both these tests, then the function will return a true value.

The regex for validating the correct email format in line 2 has been borrowed and edited slightly by adding the i flag so that the regex is case-insensitive.

The if block in lines 3-6 checks to see if the email address in the first field passes the regex check by invoking the search() method on our email string value. This method accepts regex expressions as arguments to check the string and returns the position of the specified value in the string or a -1 if no match was found. If the search() method returns a -1, then an alert would tell the user that an invalid email address has been entered and returns a false value.

Lines 7-10 checks to see if the user has entered the same string in both email fields. This is done by a simple equality check on the string values. If the strings are different, an alert warns the user that the email addresses are not the same and returns a false value.

If we have passed the two tests, then else block in lines 11-14 gets executed. An alert tells the user that he or she has done a good job and the function returns a true value so that you can continue with the form submission.

Ideally, you would have this function run during the onSubmit attribute for the form tag. This way, the form will get submitted when the checkEmail() function returns a true value. Here is an example of how your form would look like:


Email: 

Please type in your email again:

How to find and replace text dynamically via JavaScript

Knix — Fri, 07 Mar 2008 07:18:20 +0000

This is a neat little script that demonstrates two things:

1) Find – If only the Find box is filled in, then the findMyText() JavaScript function will just perform a find for the div that is given. If there is a match, the text will be highlighted and marked in bold.

2) Find and Replace – If both the Find and Replace boxes are filled in, then the findMyText() JavaScript function will do just that.

Demo

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Find
Replacment

Here is the plain HTML:


Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.




Find 
Replacment

Please excuse the use of the table for the text inputs and labels. WordPress does some automatic formatting which is annoying sometimes but it is still a great application =) The only thing of importance here is on line 9 where the onClick event executes the findMyText() function and passes 2 arguments:

Needle – This is the text that we are trying to find in the haystack of text.
Replacement – This is our replacement text for any needle that we find.

Here is our JavaScript function:

var haystackText = "";
function findMyText(needle, replacement) {
     if (haystackText.length == 0) {
          haystackText = document.getElementById("haystack").innerHTML;
     }
     var match = new RegExp(needle, "ig");     
     var replaced = "";
     if (replacement.length > 0) {
          replaced = haystackText.replace(match, replacement);
     }
     else {
          var boldText = "\"background-color: yellow; display: inline; font-weight: bold;\">" + needle + "
";
          replaced = haystackText.replace(match, boldText);
     }
     document.getElementById("haystack").innerHTML = replaced;
}

Like many of the scripts that you see here, using the JavaScript DOM objects is the key to doing the find and replace dynamically for our website.

The script asks for two parameters: the needle which we are looking for in our text and the text we want to replace it with. Please note that the replacement text is totally optional. If no replacement text is given, then the behavior of the function changes a bit.

The haystackText variable is outside of the function in line 1 because we want to store the original text and always base our searches on the original text. In lines 3-5 is where we store the original text in our haystack div if it is not already set.

Line 6 creates a regular expression object where we place our needle variable along with two flags:

i – This flag causes the regular expression match to be case-insensitive.
g – This flag causes the regular expression match to be global so it matches every occurrence instead of just the first one.

Lines 8-10 checks to see if the replacement text was set. If so, we will use the replace method on our haystackText string object and feed it our match and replacement texts. The resulting string will be saved in the replaced variable.

If the replacement text was not set, the else block in lines 11-14 will be executed. We first prepare a variable of our needle that has a bit of extra styling such as a yellow background and bold text so it stands out better. Next, we just use the replace method on our haystackText string object and pass the match and replacement texts. The resulting string will be saved in the replaced variable.

Lastly, the replaced variable which contains our results is used to substitute what was originally in our haystack div.

JavaScript to select all or none of the checkboxes in a form

Knix — Thu, 28 Feb 2008 07:24:09 +0000

Here is a quick demo of the select all or none JavaScript function that automatically toggles all of your checkboxes in a given form.

Demo

This is the plain HTML of the form:


My favorite programming/scripting language is:
Select All | None

JavaScript

Perl

PHP

C++

There is nothing exciting about the HTML code except for line 3 where all the magic happens. There are 2 links in this line of code:

All - When the user clicks on this link, it will execute the selectToggle() JavaScript function and passes over 2 arguments: the value to set the checkboxes (true in this case) and the name of the form.
None - This link executes the selectToggle() JavaScript function and passes over the false value to uncheck the checkboxes and the name of the form.

Here is a peek at the selectToggle() JavaScript function:

function selectToggle(toggle, form) {
     var myForm = document.forms[form];
     for( var i=0; i < myForm.length; i++ ) { 
          if(toggle) {
               myForm.elements[i].checked = "checked";
          } 
          else {
               myForm.elements[i].checked = "";
          }
     }
}

This function basically loops through all of the inputs in the given form name that is passed over as an argument. Depending on the value of the toggle parameter, which can be true or false, each form element will checked or unchecked respectively.

How to dynamically add form elements via JavaScript

Knix — Thu, 21 Feb 2008 08:00:43 +0000

Not all forms are meant to be static. Sometimes, you want to allow the users to add certain parts of the form as they need them. Here is a nice example of dynamically adding inputs to your form as users need them. In addition, an input limit has been implemented in the script and it is set to 3.

Demo

Here is the plain HTML for the form:



     
          Entry 1

When the user clicks on the Add another text input button, the addInput JavaScript function is executed and given the dynamicInput argument which is the name of the div that contains all our text inputs. Here is what our JavaScript function looks like:

var counter = 1;
var limit = 3;
function addInput(divName){
     if (counter == limit)  {
          alert("You have reached the limit of adding " + counter + " inputs");
     }
     else {
          var newdiv = document.createElement('div');
          newdiv.innerHTML = "Entry " + (counter + 1) + " 
";
          document.getElementById(divName).appendChild(newdiv);
          counter++;
     }
}

There are a couple of global variables:

counter – Tracks the number inputs being added.
limit – The maximum number inputs allowed for the user to add. In this case, we are limiting the user to a maximum of 3 input texts that they can submit with the form.

The addInput JavaScript function expects a parameter, which in this case is the id of the div, to add the dynamic text inputs. Once executed, the function will first check to see if the maximum number of input texts have already been used. If so, an alert will be given stating that the limit has been reached.

If the limit has not been reached, then the else block of the code is executed. A new div element is created and the inner HTML is set with 2 things:

Entry # – The global variable, counter, keeps track of the current number of text inputs that are in the form.
The input text element – The name of these text inputs,myInputs[], is followed by square brackets to indicate that it is an array. This will be more important later on when the form is submitted using the POST method.

If the form gets submitted to a PHP file, you can easily access each input value for your myInputs array. Here is the PHP code for doing just that:

$myInputs = $_POST["myInputs"];
foreach ($myInputs as $eachInput) {
     echo $eachInput . "
";
}

This is just a sample code to echo all the text input values that were sent from the form. An array variable, $myInputsPHP, is initialized with the myInputs from the form. Then, the foreach loop will go through each value and print them out.

Here is another version of this script that adds different types of inputs such as text fields, radio buttons, checkboxes, and textareas. To simplify things, the limit functionality has been removed.

Demo

Here is the plain JavaScript code for the addAllInputs function. It accepts 2 arguments:

div id – This is the div id where all the dynamic inputs will be added to.
input type – This is the type of input that we want to add.

var counterText = 0;
var counterRadioButton = 0;
var counterCheckBox = 0;
var counterTextArea = 0;
function addAllInputs(divName, inputType){
     var newdiv = document.createElement('div');
     switch(inputType) {
          case 'text':
               newdiv.innerHTML = "Entry " + (counterText + 1) + " 
";
               counterText++;
               break;
          case 'radio':
               newdiv.innerHTML = "Entry " + (counterRadioButton + 1) + " 
";
               counterRadioButton++;
               break;
          case 'checkbox':
               newdiv.innerHTML = "Entry " + (counterCheckBox + 1) + " 
";
               counterCheckBox++;
               break;
          case 'textarea':
	       newdiv.innerHTML = "Entry " + (counterTextArea + 1) + " 
type here...";
               counterTextArea++;
               break;
          }
     document.getElementById(divName).appendChild(newdiv);
}

How to hide, show, or toggle your div

Knix — Wed, 13 Feb 2008 06:45:00 +0000

Are you trying to find a way to hide and show your content? The demo below shows a simple yet elegant way of toggling your content and toggling the control text via Javascript and styling.

Demo

Let's use images! click image to expand/collapse div ==>

This demo uses plus and minus images for hiding and showing your div dynamically via JavaScript.

Demo

show <== click here

Here is the sample HTML and Javascript code:

<script language="javascript"> 
function toggle() {
	var ele = document.getElementById("toggleText");
	var text = document.getElementById("displayText");
	if(ele.style.display == "block") {
    		ele.style.display = "none";
		text.innerHTML = "show";
  	}
	else {
		ele.style.display = "block";
		text.innerHTML = "hide";
	}
} 
script>
 
show <== click Here
peek-a-boo

By default, the peek-a-boo text is loaded when the page loads but the display attribute for the div that the content resides in is set to none so it is not visible to the visitor. When the link is clicked, the toggle() JavaScript functions executes and checks the value of the display style for the div that contains the content that we want to toggle.

If the display style is none, the function will:

Set the display style to block - This is executed in the else block of the function. The inner HTML content of a DOM element with a block display setting will be visible unless it is furthered controlled by CSS styling.
Change the link text to hide - The inner HTML of the link text, which in this case is just show, is replaced with the hide text.

If the display style is block, the function will:

Set the display style to none - This is executed in the if block of the function. The inner HTML content of a DOM element with the none display setting will not be visible for the viewer.
Change the link text to show - The inner HTML of the link text, which in this case is just hide, is replaced with the show text.

Here is a more reusable and flexible toggle function that takes 2 parameters: one for the div to hide/show and a second parameter for the div that contains the link text to be switched.

<script language="javascript"> 
function toggle(showHideDiv, switchTextDiv) {
	var ele = document.getElementById(showHideDiv);
	var text = document.getElementById(switchTextDiv);
	if(ele.style.display == "block") {
    		ele.style.display = "none";
		text.innerHTML = "show";
  	}
	else {
		ele.style.display = "block";
		text.innerHTML = "hide";
	}
} 
script>

If you spice up this demo with some extra CSS styling, this can look like a nice little dialog box.

Demo

Random Snippets Hide/Show Div Demo - Click here ==>

collapse

This example demonstrates how CSS styling can make this look like a window that you can collapse and restore. How cool is that?!

Here is what the CSS styling looks like:

#headerDiv, #contentDiv { float: left; width: 510px; } #titleText { float: left; font-size: 1.2em; font-weight: bold; margin: 5px 10px; } #headerDiv { background-color: #0037DB; color: #9EB6FF; } #contentDiv { background-color: #FFE694; } #myContent { margin: 5px 10px; } #headerDiv a { float: right; margin: 10px 10px 5px 5px; } #headerDiv a:hover { color: #FFFFFF; }

Here is the HTML code:


     Random Snippets Hide/Show Div Demo - Click here ==>
collapse



     This is the content that is dynamically being collapsed.

That's all there is to it! =)

Here is the toogle2 JavaScript function:

function toggle2(showHideDiv, switchTextDiv) {
	var ele = document.getElementById(showHideDiv);
	var text = document.getElementById(switchTextDiv);
	if(ele.style.display == "block") {
    		ele.style.display = "none";
		text.innerHTML = "restore";
  	}
	else {
		ele.style.display = "block";
		text.innerHTML = "collapse";
	}
}

As requested, here is an example of a JavaScript function that toggles multiple elements simultaneously. You can either toggle each DIV individually or use the button to toggle all 3 regardless of which toggle mode they are in.

Demo

collapse

Div #1

collapse

Div #2

collapse

Div #3

This demo uses the toggle2 function as previously demonstrated and a new function called toggle3. I apologize for not being very creative on the function names. Anyway, here is the JavaScript code for toggle3:

function toggle3(contentDiv, controlDiv) {
        if (contentDiv.constructor == Array) {
                for(i=0; i < contentDiv.length; i++) {
                     toggle2(contentDiv[i], controlDiv[i]);
                }
        }
        else {
               toggle2(contentDiv, controlDiv);
        }
}

Line 2 of the function checks to see if the first argument is an array or not. If it is an array, it will also assume that the second argument is an array as well. If it is an array, the script will loop through each element and execute toggle2 with each pair of elements in the arrays. Please note that this function also assumes that both arrays are in the same order such that contentDiv[3] and controlDiv[3] are a pair that refer to the same toggle element.

If the first argument is not an array, we will just pass the arguments as is to toggle2.

Here is the HTML code for the demo:

All the excitement is jammed into line 23 where we call the toggle3 function and pass over 2 arrays: one array containing all the content div ids and another array containing the header div ids. The rest is history =)

This demo was written in response to a request. We start off with some hidden divs and each click of the button will reveal one div at a time. When we have revealed all the divs, the button will disappear.

Demo

Here is the HTML code:


   
      
         First
      
      
         Second
      
         Third

The HTML code contains 3 hidden divs to start off with. The button will launch the toggle4 JavaScript function and pass over the prefix of the div IDs. Each div id is named with the prefix box and a number following the name. For example, box1, box2, and box3. This is important for our JavaScript function. In addition, it increments the counter by 1 each time. This variable is initialized in our function.

Here is the JavaScript code:

var counter = 0;
var numBoxes = 3;
function toggle4(showHideDiv) {
       var ele = document.getElementById(showHideDiv + counter);
       if(ele.style.display == "block") {
              ele.style.display = "none";
       }
       else {
              ele.style.display = "block";
       }
       if(counter == numBoxes) {
                document.getElementById("toggleButton").style.display = "none";
       }
}

Lines 1 and 2 will initialize two very important variables for us:

counter - This variable will help us determine which box we will need to toggle.
numBoxes - This variable represents the total number of boxes. This is important for us to know when we should hide the button.

Line 4 accesses the div we will need to toggle based on the name that is passed over as the argument and the counter. When these 2 values are concatenated, we get the name of the div we will need to toggle.

Lines 5-10 tells the same old story as before for toggling the content.

Lines 11-13 tests to see if we have reached our maximum number of divs to toggle. If so, it will access the toggle button and set the display attribute to none.

By popular demand, here is a demo that uses images instead of the Expand/Collapse text.

Demo

Let's use images!

This demo uses plus and minus images for hiding and showing your div dynamically via JavaScript.

Here is the HTML code:


    Let's use images!
    

This demo uses plus and minus images for hiding and showing your div dynamically via JavaScript.

Everything is pretty much the same as before except the image tag is used instead of the Expand/Collapse text.

Here is the JavaScript code:

function toggle5(showHideDiv, switchImgTag) {
        var ele = document.getElementById(showHideDiv);
        var imageEle = document.getElementById(switchImgTag);
        if(ele.style.display == "block") {
                ele.style.display = "none";
		imageEle.innerHTML = '';
        }
        else {
                ele.style.display = "block";
                imageEle.innerHTML = '';
        }
}

The toggle5 JavaScript function is pretty much the same as the rest of the toggle functions except that it switches the img tags instead of text.

Here is a new demo in response to a request where only one div is displayed at any one time.

Demo

collapse

Div #1

collapse

Here is the plain HTML code:

Clicking on the links will execute the showonlyone JavaScript function and pass on the name of the div id.

Here is the showonlyone JavaScript code:

function showonlyone(thechosenone) {
      var newboxes = document.getElementsByTagName("div");
            for(var x=0; x<newboxes.length; x++) {
                  name = newboxes[x].getAttribute("name");
                  if (name == 'newboxes') {
                        if (newboxes[x].id == thechosenone) {
                        newboxes[x].style.display = 'block';
                  }
                  else {
                        newboxes[x].style.display = 'none';
                  }
            }
      }
}

Thanks to Justin and Ulysses for helping out with the IE6 bug that was there =)

Line 2 will find all our divs with the newboxes name attribute and place them in an array. Lines 3-10 will loop through these divs and check to see if the id of the div matches the id that was passed over to the function. If there is a match, the function will set the display attribute to block which will make the div and all its contents visible. If the id does not match, the display attribute will be set to none which will make the div and all its contents hidden.