Javascript compare single int to int array

Question

I have two vars like so:

var numberArray = [0,10,20,30,40,50];
var chosenNumber = 20;

How do I compare chosenNumber to numberArray to access its key in the array ([2])?

Paddy · Accepted Answer · 2011-11-22 12:26:32Z

7

I think you might want to use indexOf:

var index = numberArray.indexOf(chosenNumber);

answered Nov 22, 2011 at 12:26

Paddy

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1 Comment

Royi Namir Over a year ago

so simple. so clean +1. ( my mind went to very far directions - and not this simple one...)

jAndy · Accepted Answer · 2011-11-22 12:32:40Z

1

I'm not so sure what you're trying to achieve, but it sounds like you want to grab the index?

If so, use .indexOf() like

numberArray.indexOf( chosenNumber ); // 2

If you pass in a value to .indexOf() which can not get found in the array, it returns -1 instead. Since Arrays in ECMAscript are just "special" Objects, each key behind a value is just the numerical index.

numberArray = {
    0: 0,
    1: 10,
    2: 20,
    3: 30 // and so forth
};

If we would create a new Object that inherits from Array.prototype and also give it a length property, tada, we would have just created a Javascript Array.

edited Nov 22, 2011 at 12:32

answered Nov 22, 2011 at 12:26

jAndy

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1 Comment

manatwork Over a year ago

For not found returns -1, not undefined.

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