Javascript: how to access property whose name is dynamic? [duplicate]

Question

Possible Duplicate:
Javascript create variable from its name

The code below checks to see if the javascript object form_errors has the property whose name is specified by this.name, where this refers to a text input

if (form_errors.hasOwnProperty(this.name)) {
  alert(form_errors.<this.name>;
}

How can I access the property without hard-coding the property name but leaving in the generalized form this.name ? Thanks.

zneak · Accepted Answer · 2011-08-16 19:01:17Z

10

Use brackets:

form_errors[this.name]

You can access any property of an object by passing in a string with its name. For instance, foo.bar and foo['bar'] have the same result.

answered Aug 16, 2011 at 19:01

zneak

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4 Comments

Dennis Over a year ago

Just keep in mind foo['i-like-hyphens'] can only be accessed with brackets.

abhishek Over a year ago

Actually in javascript everything is arrays. Even JSON are arrays with different data types. So Braces are the best option.

zzzzBov Over a year ago

@abhishek, You're incorrect. Everything in JS is an object, it just happens that arrays are a special form of object. Try typeof [] in the console.

zneak Over a year ago

@abhishek, aside from the type hierarchy remark, I'd say that whether to use brackets or the dot notation is a question of circumstances. In case of statical accesses, using the dot notation is 3 characters shorter and doesn't imply any strings (which is more refactor-friendly), so in my opinion, it's better to stick to it until you come to a point where it's impossible (such as the situation noted by Dennis, or OP's situation).

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