[javascript] How to fill a Javascript object literal with many static key/value pairs efficiently?

The typical way of creating a Javascript object is the following:

var map = new Object();
map[myKey1] = myObj1;
map[myKey2] = myObj2;

I need to create such a map where both keys and values are Strings. I have a large but static set of pairs to add to the map.

Is there any way to perform something like this in Javascript:

var map =  { { "aaa", "rrr" }, { "bbb", "ppp" } ... };

or do I have to perform something like this for each entry:

map["aaa"]="rrr";
map["bbb"]="ppp";
...

Basically, remaining Javascript code will loop over this map and extract values according to criterias known 'at runtime'. If there is a better data structure for this looping job, I am interested too. My objective is to minimize code.

This question is related to javascript object-literal static-initialization

The answer is


The syntax you wrote as first is not valid. You can achieve something using the follow:

var map =  {"aaa": "rrr", "bbb": "ppp" /* etc */ };

It works fine with the object literal notation:

var map = { key : { "aaa", "rrr" }, 
            key2: { "bbb", "ppp" } // trailing comma leads to syntax error in IE!
          }

Btw, the common way to instantiate arrays

var array = [];
// directly with values:
var array = [ "val1", "val2", 3 /*numbers may be unquoted*/, 5, "val5" ];

and objects

var object = {};

Also you can do either:

obj.property     // this is prefered but you can also do
obj["property"]  // this is the way to go when you have the keyname stored in a var

var key = "property";
obj[key] // is the same like obj.property

In ES2015 a.k.a ES6 version of JavaScript, a new datatype called Map is introduced.

let map = new Map([["key1", "value1"], ["key2", "value2"]]);
map.get("key1"); // => value1

check this reference for more info.


Give this a try:

var map = {"aaa": "rrr", "bbb": "ppp"};