JavaScript & PHP checkbox select all

Question

I have problem with select checkbox with the JavaScript in the HTML file. I know how to do this but in my form all checkbox have name='chk[]':

<form name="forms" action='index.php' method='post'>
    <input type='checkbox' name='chk[]' value='value1'> ANY VALUE 1 </br>
    <input type='checkbox' name='chk[]' value='value2'> ANY VALUE 2 </br>
    <input type='checkbox' name='chk[]' value='value3'> ANY VALUE 3 </br>
    <input type='checkbox' name='chk[]' value='value4'> ANY VALUE 4 </br>
    <input type='submit' name='submit' value='Get Value'>
</form>

In my PHP file I use select checkbox:

<?php
    $s = "";
    $value = $_POST['chk'];

    $s .= join(", ", $value);

    echo $s;

But how can I create a function in JavaScript which checks the field. I've also tried this

Include the HTML for the checkboxes that is generated by your PHP code in the question, as well as the Javascript code you've tried that doesn't work, please. — Anthony Grist
– Anthony Grist, Commented Feb 21, 2012 at 16:51
So you want a script that checks all the checkboxes? Would it make sense to do this when the form is rendered, or is this a convenience button for the user to one-click and check all the boxes? — Surreal Dreams
– Surreal Dreams, Commented Feb 21, 2012 at 16:56

Dennis · Accepted Answer · 2012-02-21 17:13:44Z

2

To check all checkboxes dynamically, you can use the follwing code:

var inputs = document.getElementsByTagName("input");
for(var i = 0; i < inputs.length; i++)
    if(inputs[i].type == "checkbox")
        inputs[i].checked = true;

To check a checkbox by default, just add checked='checked' to the tag:

<input type='checkbox' name='chk[]' value='value' checked='checked'>

edited Feb 21, 2012 at 17:13

answered Feb 21, 2012 at 17:06

Dennis

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2 Comments

ThiefMaster Over a year ago

Replace 'checked' with true. You are accessing the boolean property, not the string attribute.

quba88 Over a year ago

Ok thx it's work fine now. I must create dynamic check, uncheck checbox in site generate by php. I don't know hove much was checkbox, and I need take it value.

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