Let’s say you are looking for a way to store some statistics like you would do in other languages like C# and you are wondering if there is a Hashtable or something like Dictionary in JavaScript which could serve the purpose.
Then, keep reading the below options and examples that might come handy for this scenario …
Use JavaScript objects as associative arrays.
Associative Array: In simple words associative arrays use Strings instead of Integer numbers as index.
Create an object with
var dictionary = {};
JavaScript allows you to add properties to objects by using the following syntax:
Object.yourProperty = value;
An alternate syntax for the same is:
Object["yourProperty"] = value;
If you can, also create key-to-value object maps with the following syntax:
var point = { x:3, y:2 };
point["x"] // returns 3
point.y // returns 2
You can iterate through an associative array using the for..in loop construct as follows
for(var key in Object.keys(dict)){
var value = dict[key];
/* use key/value for intended purpose */
}
All modern browsers support a JavaScript Map object. There are a couple of reasons that make using a Map better than Object:
An Object has a prototype, so there are default keys in the map.
The keys of an Object are Strings, where they can be any value for a Map.
You can get the size of a Map easily while you have to keep track of size for an Object.
Example:
var myMap = new Map();
var keyObj = {},
keyFunc = function () {},
keyString = "a string";
myMap.set(keyString, "value associated with 'a string'");
myMap.set(keyObj, "value associated with keyObj");
myMap.set(keyFunc, "value associated with keyFunc");
myMap.size; // 3
myMap.get(keyString); // "value associated with 'a string'"
myMap.get(keyObj); // "value associated with keyObj"
myMap.get(keyFunc); // "value associated with keyFunc"
If you want keys that are not referenced from other objects to be garbage collected, consider using a WeakMap instead of a Map.
Resources you might find useful:
Get the book: Javascript Challenges
source: https://stackoverflow.com/questions/1208222/how-to-do-associative-array-hashing-in-javascript
Other Dev posts:
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