How To Create Associative Array In EcmaScript

Question

I want to create an associative array within the constructor. But the below code throws error. Uncaught TypeError: Cannot set property 'num' of undefined

class Validate{

    constructor(){

        this.name['num'] = ['one','two'];
    }
    display() {




        console.log(this.name['num']);
    }



}

JavaScript does not have associative arrays, so you can't create one. — , Nov 21 '16 at 16:37
Just a wild guess, but maybe the problem is that it cannot set property `num` of undefined. — , Nov 21 '16 at 16:44

n00dl3 · Answer 1 · 2016-11-22T08:20:21.427

3

Javascript has no associative array, but Object literal can be used as an alternative. Here, you need to define the object before using it.

class Validate{
    constructor(){
        this.name={}//define this.name
        this.name['num'] = ['one','two'];
    }
    display() {
        console.log(this.name['num']);
    }
}

edited Nov 22 '16 at 08:20

answered Nov 21 '16 at 16:39

n00dl3

21,213
7
66
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Artur Hovhannisyan · Accepted Answer · 2016-11-21T16:58:34.353

0

You will initialize name and after that use property of your object . In this case name is not defined and you try to set property of undefined.

class Validator
{
  
  constructor(){

        this.name = {num :['one','two']} ;
        
    }
    display() {


       

        console.log(this.name['num']);
    } 
}
 var validator = new Validator();
validator.display();

edited Nov 21 '16 at 16:58

answered Nov 21 '16 at 16:38

Artur Hovhannisyan

94
6

1

For questions like these, the _explanation_ of the problem is far more important than a solution that is “ready to copy”. – Sebastian Simon Nov 21 '16 at 16:40
because name is not defined and you try to set property of undefined. – Artur Hovhannisyan Nov 21 '16 at 16:43
1

This is not an associative array, whatever that is. It's an object. – Nov 21 '16 at 16:43
@ArturHovhannisyan Edit your answer. Don’t put the most important part in the comments. – Sebastian Simon Nov 21 '16 at 16:56
@Xufox thank for advice – Artur Hovhannisyan Nov 21 '16 at 16:59
@ArturHovhannisyan thank u !!! – Dilkush Nov 22 '16 at 09:25

How To Create Associative Array In EcmaScript

2 Answers2