CODEWITHSUNDEEP
javascriptarrayshashmap
usr30911
usr30911

Reputation: 2791

Convert array to Hashmap (key value pair) javascript

I have an array named territory which contains the following

enter image description here

i want to create a hashmap where the

key is the id [id atribute of each object wihin territory]

and the

value is the entire object

any help/pointers on the same?

thankyou

Upvotes: 2

Views: 8411

Answers (2)

babar78
babar78

Reputation: 131

hi you could do like that and it will work : 

var hashmap = {};

territory.forEach(function(element) {

    if(hashmap[element.id]!==null && hashmap[element.id]!=undefined){
       if(!Array.isArray(hashmap[element.id])){ 
           var tempObj = hashmap[element.id];

           // don't forget to json.stringify your object if you 
           // want to  serialise your hashmap for external use

           hashmap[element.id] = [tempObj];
       }

       hashmap[element.id].push(element);

    }
    else{
        // if you want to serialise your hashmap for external use
        hashmap[element.id] = JSON.stringify(element);
        // if not, you could just do without JSON.stringify
        hashmap[element.id] = element;
    }

});

console.log(hashmap);

you could look at mozilla documentation for more informations on foreach

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach

Edit : I updated the code to avoid (dirty) id duplication and store object who share the same id

Upvotes: 2

ssube
ssube

Reputation: 48247

You simply need to iterate over the array and assign each element as a property in an object:

var hash = {};
var data = [...];
data.forEach(function (it) { hash[it.id] = it; });

If you have access to the lodash library, you can use indexBy to transform the whole array at once:

var data = [...];
var hash = _.indexBy(data, 'id');

The underscore library also has an indexBy method that behaves in the same fashion.

Upvotes: 5

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