How can I change onclick behavior of button dynamically using javascript?
Here is what I meant:
I have following buttons:
<button class="num" onclick="getval(0)">0</button>
<button class="num" onclick="getval(1)">1</button>
<button class="num" onclick="getval(2)" >2</button>
<button class="num" onclick="getval(3)" >3</button>
function getval(){
...............
}
function getvalNew(){
..............
}
How can I make the buttons to switch from getval() to getvalNew() and reset it again?
How can I change onclick behavior of button dynamically using javascript?
Here is what I meant:
I have following buttons:
<button class="num" onclick="getval(0)">0</button>
<button class="num" onclick="getval(1)">1</button>
<button class="num" onclick="getval(2)" >2</button>
<button class="num" onclick="getval(3)" >3</button>
function getval(){
...............
}
function getvalNew(){
..............
}
How can I make the buttons to switch from getval() to getvalNew() and reset it again?
Share Improve this question asked Jun 24, 2013 at 14:13 Jack_of_All_TradesJack_of_All_Trades 11.5k20 gold badges63 silver badges95 bronze badges 3- 2 It's easier if you don't use inline event handlers. For more information about event handling see quirksmode/js/introevents.html. – Felix Kling Commented Jun 24, 2013 at 14:15
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1
see @FelixKling's ment for why not to use inline event handlers, but if you have to, you could try using js to change the onclick attribute of the element. I'm a bit rusty with pure js but you could try something like
jQuery('button.num').attr('onclick', 'myFunc(1)');if you were to use jQuery. – totallyNotLizards Commented Jun 24, 2013 at 14:15 - A simple switch statement with a different variable or array or global true falses would work. You can also just onclick do a this. and change the onclick attr to be the opposite function. – abc123 Commented Jun 24, 2013 at 14:16
6 Answers
Reset to default 3Here's an approach, based on my blank.html template.
Note: in setAllFunc3, you could attach several handlers to the one element. You can also remove them selectively. See another member's note about getAllByClassName.
Also note: by attaching the handler, we get access to the this var. This means we know which element triggered the call. I have simply extracted the text from the button. You could instead get the value for an attribute, that you then use in the handler.
Probably something for you to discover a little later. :)
<!DOCTYPE html>
<html>
<head>
<script>
function byId(e){return document.getElementById(e);}
function newEl(tag){return document.createElement(tag);}
function newTxt(txt){return document.createTextNode(txt);}
function toggleClass(element, newStr)
{
index=element.className.indexOf(newStr);
if ( index == -1)
element.className += ' '+newStr;
else
{
if (index != 0)
newStr = ' '+newStr;
element.className = element.className.replace(newStr, '');
}
}
function forEachNode(nodeList, func)
{
var i, n = nodeList.length;
for (i=0; i<n; i++)
{
func(nodeList[i], i, nodeList);
}
}
window.addEventListener('load', mInit, false);
function mInit()
{
}
function getval(inputVar)
{
alert(inputVar + " was passed to getval");
}
function getvalNew(inputVar)
{
alert("getvalNew(" + inputVar + ")");
}
function setAllFunc1()
{
var tgtButtons = document.getElementsByClassName('num');
var i, n = tgtButtons.length;
for (i=0; i<n; i++)
tgtButtons[i].setAttribute('onclick', 'getval(' + i + ')' );
}
function setAllFunc2()
{
var tgtButtons = document.getElementsByClassName('num');
var i, n = tgtButtons.length;
for (i=0; i<n; i++)
tgtButtons[i].setAttribute('onclick', 'getvalNew(' + i + ')' );
}
function myFunc3()
{
var clickedBtn = this;
var btnText = clickedBtn.innerHTML;
alert("You clicked the button labelled: " + btnText);
}
function setAllFunc3()
{
var tgtButtons = document.getElementsByClassName('num');
var i, n = tgtButtons.length;
for (i=0; i<n; i++)
{
tgtButtons[i].removeAttribute('onclick');
tgtButtons[i].addEventListener('click', myFunc3);
}
}
</script>
<style>
</style>
</head>
<body>
<button class="num" onclick="getval(0)">0</button>
<button class="num" onclick="getval(1)">1</button>
<button class="num" onclick="getval(2)">2</button>
<button class="num" onclick="getval(3)">3</button>
<hr>
Simple method - using attributes
<input type='button' onclick='setAllFunc1()' value='set all to "getval()"'/>
<input type='button' onclick='setAllFunc2()' value='set all to "getvalNew()"'/>
<hr>
Better method - using addEventListener
<input type='button' onclick='setAllFunc3()' value='set all to "myFunc3()"'/>
</body>
</html>
function getval() {
........
var buttons = document.getElementsByClassName("num");
for (i=0;i<buttons.length;i++){
buttons[i].onclick = function(){
getvalNew();
}
}
}
And vice versa for the other function. At least, this should work....
you can do something like this:
code
$(".num").on("click", function () {
if ($(this).hasClass("getval")) {
$(this).removeClass("getval").addClass("getvalnew");
//do what you need here
alert("getVal");
} else {
$(this).removeClass("getvalnew").addClass("getval");
//do what you need here
alert("getValNew");
}
});
FIDDLE
http://jsfiddle/ygqrU/
You can do this with single liner JQuery syntax with your conditional statements when you want to change the function mapping.
//bind all
$('.num').bind('click', getValNew());
//Unbind all
$('.num').unbind('click');
In case the browser does not support getElementsByClassName, this is an alternative:
var elems = document.getElementsByTagName('button');
for (i=0;i<elems.length;i++) {
if(elems[i].className == "num") {
elems[i].onclick = function(){
getvalNew();
}
}
Maybe something like this:
.
var button = document.getElementsByClassName("num")
// You could also do: var button = document.getElementsByTagName("button")
function set() { // Change all the buttons onclick event to getvalNew
for (i = 0; i < button.length; i++) {
button[i].onclick = function() {
getvalNew(i)
}
}
}
function reset() { // Change all the buttons onclick event back to getval
for (i = 0; i < button.length; i++) {
button[i].onclick = function() {
getval(i)
}
}
}