JavaScript associate array

javascript associative-array
MxLDevs picture MxLDevs · Mar 25, 2011 · Viewed 48k times · Source

In Python I could do something like myMap = {key: [value1, value2]} and then access the value2 using myMap[key][1]

Can I do something like this in JavaScript?

Answer

Pointy picture Pointy · Mar 25, 2011

Well, you can do this:

var myMap = { key: [ value1, value2 ] };
var array = myMap.key; // or myMap["key"]

JavaScript doesn't have an "associative array" type, one that combines "map" behavior with array behavior like keeping track of the number of properties. Thus the common thing to do is use a plain object. In modern JavaScript now (2017), there's an explicit Map facility that allows keys to be of any type, not just strings as when using simple objects.

JavaScript is a little bit silly about the object literal notation, in that it won't let you use reserved words for keys unless you quote them:

var myMap = { 'function': 'hello world' };

The quote syntax allows any string to be used as a property name. To access such properties, you'd use the [ ] operator

console.log(myMap["function"]); // "hello world"

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