jQuery hasAttr checking to see if there is an attribute on an element

How do you check if there is an attribute on an element in jQuery? Similar to hasClass, but with attr?

For example,

if ($(this).hasAttr("name")) {
    // ...
}

var attr = $(this).attr('name');

// For some browsers, `attr` is undefined; for others,
// `attr` is false.  Check for both.
if (typeof attr !== 'undefined' && attr !== false) {
    // ...
}

How about just $(this).is("[name]")?

The [attr] syntax is the CSS selector for an element with an attribute attr, and .is() checks if the element it is called on matches the given CSS selector.

If you will be checking the existence of attributes frequently, I would suggest creating a hasAttr function, to use as you hypothesized in your question:

$.fn.hasAttr = function(name) {  
   return this.attr(name) !== undefined;
};

$(document).ready(function() {
    if($('.edit').hasAttr('id')) {
        alert('true');
    } else {
        alert('false');
    }
});

<div class="edit" id="div_1">Test field</div>

You're so close it's crazy.

if($(this).attr("name"))

There's no hasAttr but hitting an attribute by name will just return undefined if it doesn't exist.

This is why the below works. If you remove the name attribute from #heading the second alert will fire.

Update: As per the comments, the below will ONLY work if the attribute is present AND is set to something not if the attribute is there but empty

<script type="text/javascript">
$(document).ready(function()
{
    if ($("#heading").attr("name"))
      alert('Look, this is showing because it\'s not undefined');
    else
      alert('This would be called if it were undefined or is there but empty');
});
</script>
<h1 id="heading" name="bob">Welcome!</h1>

Late to the party, but... why not just this.hasAttribute("name")?

Refer This

The best way to do this would be with filter():

$("nav>ul>li>a").filter("[data-page-id]");

It would still be nice to have .hasAttr(), but as it doesn't exist there is this way.

Object.prototype.hasAttr = function(attr) {
    if(this.attr) {
        var _attr = this.attr(attr);
    } else {
        var _attr = this.getAttribute(attr);
    }
    return (typeof _attr !== "undefined" && _attr !== false && _attr !== null);      
};

I came a crossed this while writing my own function to do the same thing... I though I'd share in case someone else stumbles here. I added null because getAttribute() will return null if the attribute does not exist.

This method will allow you to check jQuery objects and regular javascript objects.

You can also use it with attributes such as disabled="disabled" on the form fields etc. like so:

$("#change_password").click(function() {
	var target = $(this).attr("rel");
	if($("#" + target).attr("disabled")) {
		$("#" + target).attr("disabled", false);
	} else {
		$("#" + target).attr("disabled", true);
	}
});

The "rel" attribute stores the id of the target input field.

I wrote a hasAttr() plugin for jquery that will do all of this very simply, exactly as the OP has requested. More information here

EDIT: My plugin was deleted in the great plugins.jquery.com database deletion disaster of 2010. You can look here for some info on adding it yourself, and why it hasn't been added.