CODEWITHSUNDEEP
javascript
Ranger 22
Ranger 22

Reputation: 445

JavaScript, array A length is 0 but A[key] has value

Here is the code

var A = [];
A['key1'] = 'apple';
console.log(A.length);
console.log(A['key1']);

A.length is 0 in the log.... But I just don't get it, apparently A['key1'] has a value 'apple'. Why A.length is 0?

Upvotes: 1

Views: 1420

Answers (2)

Neelakandan Sivathanu
Neelakandan Sivathanu

Reputation: 55

You are using javascript associative array which don't have the built-in function like length to get the number of properties in the array. So Instead of using length function you can use the following line to get the number of properties in the array.

      Object.keys(A).length

Upvotes: 1

prasanth
prasanth

Reputation: 22500

Your are define A is array .Array is not key and value pair,Object only have key value pair

Check the console.log A its still empty 

 var A = [];
    A['key1'] = 'apple';//its not added because is a array
    console.log(A);    
    console.log(A.length);

If you need to add key value pair Define A as a Object.and find the length using Object.keys(A) .It will create array of the Object keys

var A = {};
    A['key1'] = 'apple';
    console.log(A);    
    console.log(Object.keys(A).length);
    console.log(A.key1.length)

Better see the Difference between an array and an object?

Upvotes: 4

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