I have a input tag with an onblur event listener:
<input id="myField" type="input" onblur="doSomething(this)" />
Via JavaScript, I want to trigger the blur event on this input so that it, in turn, calls the doSomething function.
My initial thought is to call blur:
document.getElementById('myField').blur()
But that doesn't work (though no error).
This does:
document.getElementById('myField').onblur()
Why is that? .click() will call the click event attached to an element via the onclick listener. Why does blur() not work the same way?
This:
document.getElementById('myField').onblur();
works because your element (the <input>) has an attribute called "onblur" whose value is a function. Thus, you can call it. You're not telling the browser to simulate the actual "blur" event, however; there's no event object created, for example.
Elements do not have a "blur" attribute (or "method" or whatever), so that's why the first thing doesn't work.
Contrary to what pointy says, the blur() method does exist and is a part of the w3c standard. The following exaple will work in every modern browser (including IE):
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title>Javascript test</title>
<script type="text/javascript" language="javascript">
window.onload = function()
{
var field = document.getElementById("field");
var link = document.getElementById("link");
var output = document.getElementById("output");
field.onfocus = function() { output.innerHTML += "<br/>field.onfocus()"; };
field.onblur = function() { output.innerHTML += "<br/>field.onblur()"; };
link.onmouseover = function() { field.blur(); };
};
</script>
</head>
<body>
<form name="MyForm">
<input type="text" name="field" id="field" />
<a href="javascript:void(0);" id="link">Blur field on hover</a>
<div id="output"></div>
</form>
</body>
</html>
Note that I used link.onmouseover instead of link.onclick, because otherwise the click itself would have removed the focus.
I guess it's just because the onblur event is called as a result of the input losing focus, there isn't a blur action associated with an input, like there is a click action associated with a button
来源：https://stackoverflow.com/questions/5212651/blur-vs-onblur