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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 create your own customized calculator via JavaScript

Knix — Sun, 27 Apr 2008 01:01:51 +0000

This is a simple example of implementing a calculator with JavaScript and HTML. This calculator will only have the division, multiplication, addition, and subtraction operators but you can easily tack on more functions if needed.

Demo

Here is the html code including the CSS stuff:



Demo

Most of the HTML is coding for all the input buttons and their associated onclick event handlers. All the buttons, except for the = button, will call the pushButton JavaScript when clicked and passes it’s associated value. The = button calls the calculate JavaScript function and passes the value that is in the text input which represents the string of numbers and operators that were pushed. The rest of the HTML is just icing on the cake so that it actually looks like a calculator.

Here is the JavaScript code for the 2 functions:

function pushButton(buttonValue) {
     if (buttonValue == 'C') {
          document.getElementById('screen').value = '';
     }
     else {
          document.getElementById('screen').value += buttonValue;
     }
}
function calculate(equation) {
     var answer = eval(equation);
     document.getElementById('screen').value = answer;
}

The pushButton function does 2 things for us. If the user clicks on the C button or the clear button, it accesses the text input object, which represents our calculator screen, via the DOM . Once it is accessed, the value inside the text input is set to ” (2 single quotes) which is an empty string. This will basically remove whatever string is already inside the text input. If the user clicks on any other button, the function will access the text input object and append the value that was passed over to whatever is already in our text input. This allows us to build our string with numbers and operators.

The calculate function does exactly what it’s name suggests. It takes our string of numbers and operators and evaluates it in line 10. The eval() function treats the string as if it were JavaScript code and executes it and returns the results. The function will then access the text input object and replace whatever the current value is with the answer from the eval() function.

That’s it!

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 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.

Dynamic Country State Javascript Menu Example

Knix — Sat, 09 Feb 2008 07:36:02 +0000

I have found myself in a couple of situations where I needed a simple dynamic javascript menu where the user would make a selection from one select list and depending on what the user selected from the first select list a second list would offer further options. Here is a perfect example:

Demo

Country:

State/Province:

Country value:
State/Province value:

In this example, the state/province menu is disabled until the user has first selected a country. Then depending on the country that is chosen, the list of associated states or provinces would follow. For the sake of simplicity, only the state/province menus have been implemented for the United States and Canada. If any other country is chosen, the value for the state input defaults to Other.

Here is the HTML code for the example:

Country:

State/Province:

Country value:
State value:

After the user makes a country selection, the Javascript onChange event is fired and executes the printStateMenu Javascript function and passes the value of the country that was chosen as an argument. The table just displays the current values of the country and state select inputs. Please note that the script source path on line 1 will have to edited depending on where you store the JavaScript function. Here is the Javascript code for the printStateMenu function:

function printStateMenu(country) {     
	var stateSelect = '';
	if (country == 'US') {
		stateSelect = '';
	}
	else if (country == 'CA') {
		stateSelect = '';
	}
	else {
		stateSelect = '';
	}
	document.getElementById('stateSelect').innerHTML = stateSelect;
	document.getElementById('countryValue').innerHTML = document.getElementById('country').value;
	document.getElementById('stateValue').innerHTML = document.getElementById('state').value;
}

This Javascript function is pretty simple. It looks at the country value that was selected and creates the corresponding state/province menu. Then it replaces the HTML code in the stateSelect DOM element with the new select menu. The state/province select inputs for US and Canada also have an onChange event that displays the chosen value of the state input into the table. The select menu for any other country will just return a disabled select menu and default to the Other value for the state input.