javascript - Change value of checkbox based on value of other form -

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• how implement “select all” check box in html? 23 answers

i'm trying have checkbox called 'all' when checked, checks rest of checkboxes in form. have no javascript experience sorry if basic. patched looking @ posts this , this.

<script type="text/javascript"> function checkit(checkbox) {   document.getelementbyid("1").checked = true;   document.getelementbyid("2").click();  } </script> 

my html looks this:

<form>   <input type="checkbox" id="a" onclick="checkit(this)">all<br></input>   <input type="checkbox" id="1">one<br></input>   <input type="checkbox" id="2">two<br></input> </form> 

how can checkboxes 1 , 2 change when select checkbox all? thanks.

since not familiar javascript, suggest looking jquery javascript library. many coders find simpler learn/use, , there no debate requires less typing.

here introductory jquery tutorials if curious.

to solve problem, added class checkboxes wish automatically check/uncheck, , used class check/uncheck boxes.

working jsfiddle here

html:

<form>   <input type="checkbox" id="a">all<br></input>   <input type="checkbox" class="cb" id="1">one<br></input>   <input type="checkbox" class="cb" id="2">two<br></input> </form> 

jquery:

$('#a').click(function() {    // alert($(this).prop('checked'));     if ($(this).is(':checked') == true) {         $('.cb').prop('checked', true);     }else{         $('.cb').prop('checked', false);     } }); 

note solution uses jquery, need jquery library loaded (usually put line in head tags):

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>