call javascript object method with a variable

Question

i am new to object oriented javascript. I have a variable whose value i would like to use to call an object's method. like this..

var foo = {
    bar: function() {},
    barr: function() {}
}

now there is a variable whose value can be any of the two method's names bar and barr i want to call them with something like

var myvar = 'bar';
foo.{myVar}();

If you are starting to learn JavaScript, this may be a nice article to read: John Resig's Learning Advanced Javascript. I know it says "advanced", but it starts from basic examples, and has a nice interactive interface for modifying and running the code. — vgru
– vgru, Commented Jul 18, 2011 at 19:04
@Groo hey! thanks alot! a am new to object stuff and TBH they are a bit confusing.. :O but i am on it :D — Achshar
– Achshar, Commented Jul 18, 2011 at 19:06

pixelfreak · Accepted Answer · 2011-07-18 18:54:50Z

52

So I assume you want to call the appropriate function dynamically based on a string. You can do something like this:

var myVar = 'bar';
foo[myVar]();

Or you can also use eval but this is riskier (prone to injection attack) and slower (don't do this! :P):

var myVar = 'bar';
eval('foo.' + myVar + '()');

answered Jul 18, 2011 at 18:54

pixelfreak

17.9k12 gold badges92 silver badges110 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Achshar Over a year ago

thanks.. there are so many answers :O looks like i asked a n00b question :P but hey thanks every body :)

pixelfreak Over a year ago

There is no n00b question except the one that was just answered :)

Achshar Over a year ago

:D so apparently they work like arrays too.. we can call them like we call an array array['key']. interesting. thnx!

jfriend00 Over a year ago

@Achshar - In your example, foo is an object. All objects can access their properties with array-type syntax. It isn't really an array (which is why I wrote this comment to make sure you don't think it's an array), but you can use the foo['x'] syntax to access the properties just the same as you can use foo.x.

Achshar Over a year ago

@jfriend00 oh yeaa i know that right :) i was just wondering that the syntax is same so that devs don't have to remember a bunch of different syntaxes for all the different things in the language :D

|

yan · Accepted Answer · 2011-07-18 18:55:03Z

11

Since you can access elements of an object via subscript notation, the following will do what you're looking for:

var myVar = 'bar';
foo[myVar]();

answered Jul 18, 2011 at 18:55

yan

21k3 gold badges41 silver badges48 bronze badges

Comments

Justin Ethier · Accepted Answer · 2011-07-18 18:55:16Z

8

You can just say:

foo[myVar]();

Since foo is a JavaScript object, this code will reference the member by name contained in the myVar variable.

answered Jul 18, 2011 at 18:55

Justin Ethier

135k53 gold badges235 silver badges290 bronze badges

Comments

wanovak · Accepted Answer · 2011-07-18 18:56:12Z

5

var foo = {
    bar: function() { alert('bar'); },
    barr: function() { alert('barr'); }
}


var myvar = 'bar';
foo[myvar](); // alert 'bar'

answered Jul 18, 2011 at 18:56

wanovak

6,12727 silver badges32 bronze badges

Comments

Mrchief · Accepted Answer · 2011-07-18 18:55:19Z

4

Use something like: foo[myVar]();

answered Jul 18, 2011 at 18:55

Mrchief

76.4k20 gold badges145 silver badges193 bronze badges

1 Comment

Scott Over a year ago

calling inside the object methods this way doesn't seem to work. using try/catch the message says 'this[myVar] is not a function'

John Hartsock · Accepted Answer · 2011-07-18 18:55:48Z

4

it should be something like this

foo[myvar]();

answered Jul 18, 2011 at 18:55

John Hartsock

87.1k23 gold badges135 silver badges146 bronze badges

Collectives™ on Stack Overflow

call javascript object method with a variable

6 Answers 6

6 Comments

Comments

Comments

Comments

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

6 Comments

Comments

Comments

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related