jQuery hasAttr checking to see if there is an attr

Question

Possible Duplicate:
Check existence of an attribute with JQuery

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")) {
    // ...
}

Answer 1

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.

Answer 2

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

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

Answer 3

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.

Answer 4

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.

Answer 5

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>

Answer 6

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.