How do find the id of the button which is being clicked?

<button onClick="reply_click()"></button> <button onClick="reply_click()"></button> <button onClick="reply_click()"></button> function reply_click() { }

17 Answers

You need to send the ID as the function parameters. Do it like this:

<button onClick="reply_click(this.id)">B1</button> <button onClick="reply_click(this.id)">B2</button> <button onClick="reply_click(this.id)">B3</button> <script type="text/javascript"> function reply_click(clicked_id) { alert(clicked_id); } </script>

This will send the ID this.id as clicked_id which you can use in your function. See it in action here.

In general, things are easier to keep organized if you separate your code and your markup. Define all of your elements, and then in your JavaScript section, define the various actions that should be performed on those elements.

When an event handler is called, it's called within the context of the element that was clicked on. So, the identifier this will refer to the DOM element that you clicked on. You can then access attributes of the element through that identifier.

For example:

<button>Button 1</button> <button>Button 2</button> <button>Button 3</button> <script type="text/javascript"> var reply_click = function() { alert("Button clicked, id "+this.id+", text"+this.innerHTML); } document.getElementById('1').onclick = reply_click; document.getElementById('2').onclick = reply_click; document.getElementById('3').onclick = reply_click; </script>

USING PURE JAVASCRIPT: I know it's late but may be for the future people it can help:

In the HTML part:

<button onClick="reply_click()"></button> <button onClick="reply_click()"></button> <button onClick="reply_click()"></button>

In the Javascipt Controller:

function reply_click() { alert(event.srcElement.id); }

This way we don't have to bind the 'id' of the Element at the time of calling the javascript function.

(I think the id attribute needs to start with a letter. Could be wrong.)

You could go for event delegation...

<div onClick="reply_click()"> <button></button> <button></button> <button></button> </div> function reply_click(e) { e = e || window.event; e = e.target || e.srcElement; if (e.nodeName === 'BUTTON') { alert(e.id); } }

...but that requires you to be relatively comfortable with the wacky event model.

<button onClick="reply_click(this)"></button> <button onClick="reply_click(this)"></button> <button onClick="reply_click(this)"></button> function reply_click(obj) { var id = obj.id; }

<button></button> <button></button> <button></button> <script> $('.clickMe').click(function(){ alert(this.id); }); </script>

How to do it without inline JavaScript or external libraries

it is generally recommended to avoid inline JavaScript, but rarely is there an example of how to do it.
Here is my way of attaching events to buttons.
I'm not entirely happy with how much longer the recommended method is compared to a simple onClick attribute.

Modern browsers

Works before the document has finished loading.
Very efficient.
Separates JS from HTML.
JS is in the <head>

const OnEvent = (doc) => { return { on: (type, selector, callback) => { doc.addEventListener(type, (event)=>{ if(!event.target.matches(selector)) return; callback.call(event.target, event); }, false); } } }; OnEvent(document).on('click', '.btn', function (e) { let div = document.createElement("div"); div.innerHTML = "click " + e.target.id + "!"; document.body.appendChild(div); });

<button>Button 1</button> <button>Button 2</button> <button>Do nothing</button>

2014 browsers only

<button>Button</button> <script> let OnEvent = (doc) => { return { on: (event, className, callback) => { doc.addEventListener('click', (event)=>{ if(!event.target.classList.contains(className)) return; callback.call(event.target, event); }, false); } } }; OnEvent(document).on('click', 'btn', function (e) { window.console.log(this.id, e); }); </script>

2013 browsers only

<!DOCTYPE html> <html> <head> <script> (function(doc){ var hasClass = function(el,className) { return el.classList.contains(className); } doc.addEventListener('click', function(e){ if(hasClass(e.target, 'click-me')){ e.preventDefault(); doSomething.call(e.target, e); } }); })(document); function insertHTML(str){ var s = document.getElementsByTagName('script'), lastScript = s[s.length-1]; lastScript.insertAdjacentHTML("beforebegin", str); } function doSomething(event){ console.log(this.id); // this will be the clicked element } </script> <!--... other head stuff ...--> </head> <body> <!--Best if you inject the button element with javascript if you plan to support users with javascript disabled--> <script> insertHTML('<button>Button 1</button>'); </script> <!--Use this when you don't care about broken buttons when javascript is disabled.--> <!--buttons can be used outside of forms --> <button>Button 2</button> <input type="button" value="Button 3"> <!--Use this when you want to lead the user somewhere when javascript is disabled--> <a href="/path/to/non-js/action">Button 4</a> </body> </html>

Cross-browser

<!DOCTYPE html> <html> <head> <script type="text/javascript"> (function(doc){ var cb_addEventListener = function(obj, evt, fnc) { // W3C model if (obj.addEventListener) { obj.addEventListener(evt, fnc, false); return true; } // Microsoft model else if (obj.attachEvent) { return obj.attachEvent('on' + evt, fnc); } // Browser don't support W3C or MSFT model, go on with traditional else { evt = 'on'+evt; if(typeof obj[evt] === 'function'){ // Object already has a function on traditional // Let's wrap it with our own function inside another function fnc = (function(f1,f2){ return function(){ f1.apply(this,arguments); f2.apply(this,arguments); } })(obj[evt], fnc); } obj[evt] = fnc; return true; } return false; }; var hasClass = function(el,className) { return (' ' + el.className + ' ').indexOf(' ' + className + ' ') > -1; } cb_addEventListener(doc, 'click', function(e){ if(hasClass(e.target, 'click-me')){ e.preventDefault ? e.preventDefault() : e.returnValue = false; doSomething.call(e.target, e); } }); })(document); function insertHTML(str){ var s = document.getElementsByTagName('script'), lastScript = s[s.length-1]; lastScript.insertAdjacentHTML("beforebegin", str); } function doSomething(event){ console.log(this.id); // this will be the clicked element } </script> <!--... other head stuff ...--> </head> <body> <!--Best if you inject the button element with javascript if you plan to support users with javascript disabled--> <script type="text/javascript"> insertHTML('<button>Button 1</button>'); </script> <!--Use this when you don't care about broken buttons when javascript is disabled.--> <!--buttons can be used outside of forms --> <button>Button 2</button> <input type="button" value="Button 3"> <!--Use this when you want to lead the user somewhere when javascript is disabled--> <a href="/path/to/non-js/action">Button 4</a> </body> </html>

Cross-browser with jQuery

<!DOCTYPE html> <html> <head> <script type="text/javascript"> (function($){ $(document).on('click', '.click-me', function(e){ doSomething.call(this, e); }); })(jQuery); function insertHTML(str){ var s = document.getElementsByTagName('script'), lastScript = s[s.length-1]; lastScript.insertAdjacentHTML("beforebegin", str); } function doSomething(event){ console.log(this.id); // this will be the clicked element } </script> <!--... other head stuff ...--> </head> <body> <!--Best if you inject the button element with javascript if you plan to support users with javascript disabled--> <script type="text/javascript"> insertHTML('<button>Button 1</button>'); </script> <!--Use this when you don't care about broken buttons when javascript is disabled.--> <!--buttons can be used outside of forms --> <button>Button 2</button> <input type="button" value="Button 3"> <!--Use this when you want to lead the user somewhere when javascript is disabled--> <a href="/path/to/non-js/action">Button 4</a> </body> </html>

You can run this before the document is ready, clicking the buttons will work because we attach the event to the document.

Here is a jsfiddle
For some strange reason the insertHTML function does not work in it even though it works in all my browsers.

You can always replace insertHTML with document.write if you don't mind it's drawbacks

<script> document.write('<button>Button 1</button>'); </script>

Sources:

If you don't want to pass any arguments to the onclick function, just use event.target to get the clicked element:

<button onClick="reply_click()"></button> <button onClick="reply_click()"></button> <button onClick="reply_click()"></button> function reply_click() { // event.target is the element that is clicked (button in this case). console.log(event.target.id); }

With pure javascript you can do the following:

var buttons = document.getElementsByTagName("button"); var buttonsCount = buttons.length; for (var i = 0; i < buttonsCount; i += 1) { buttons[i].onclick = function(e) { alert(this.id); }; }

check it On JsFiddle

<button onClick="reply_click()"></button> <button onClick="reply_click()"></button> <button onClick="reply_click()"></button> function reply_click() { console.log(window.event.target.id) }

You can simply do it this way:

<input type="button" onclick="showId(this.id)" value="click me to show my id"/> <script type="text/javascript"> function showId(obj) { var id=obj; alert(id); }

This is improvement of Prateek answer - event is pass by parameter so reply_click not need to use global variable (and as far no body presents this variant)

function reply_click(e) { console.log(e.target.id); }

<button onClick="reply_click(event)">B1</button> <button onClick="reply_click(event)">B2</button> <button onClick="reply_click(event)">B3</button>

Button 1 Button 2 Button 3

var reply_click = function() { alert("Button clicked, id "+this.id+", text"+this.innerHTML); } document.getElementById('1').onclick = reply_click; document.getElementById('2').onclick = reply_click; document.getElementById('3').onclick = reply_click;

 <buttonclass="clickMe"></button> <button></button> <button></button> $('.clickMe').live('click',function(){ var clickedID = this.id; });

Sorry its a late answer but its really quick if you do this :-

$(document).ready(function() { $('button').on('click', function() { alert (this.id); }); });

This gets the ID of any button clicked.

If you want to just get value of button clicked in a certain place, just put them in container like

<div id = "myButtons"> buttons here </div>

and change the code to :-

 $(document).ready(function() { $('.myButtons button').on('click', function() { alert (this.id); }); });

I hope this helps

This will log the id of the element that's been clicked: addFields.

<button onclick="addFields()">+</button> <script> function addFields(){ console.log(event.toElement.id) } </script>

Although it's 8+ years late, in reply to @Amc_rtty, to get dynamically generated IDs from (my) HTML, I used the index of the php loop to increment the button IDs. I concatenated the same indices to the ID of the input element, hence I ended up with and button and so on.

$tableView .= "<td><input type='hidden' value='http://".$_SERVER['HTTP_HOST']."/sql/update.php?id=".$mysql_rows[0]."&table=".$theTable."'id='tableview".$mysql_rows[0]."'><button type='button' onclick='loadDoc(event)' id='".$mysql_rows[0]."'>Edit</button></td>";

In the javascript, I stored the button click in a variable and added it to the element.

function loadDoc(e) { var btn = e.target.id; var xhttp = new XMLHttpRequest(); var page = document.getElementById("tableview"+btn).value; //other Ajax stuff }