Build Json from an array of objects

Question

I'm trying to use typescript to build a json object from an array of objects like this one:[

[
  { attribute: 'a', modifier: 121 },
  { attribute: 'b', modifier: 67 },
  { attribute: 'c', modifier: 121 },
  { attribute: 'd', modifier: 67 } 
]

I would like to get something like:

{
  a:  121,
  b:  67,
  c:  121,
  d:  67  
}

But I just can't get my head around the high order functions to make it work.

Answer 1

You could use reduce method which accepts as parameter a callback function.

Read more about reduce method here .

 let array=[ { attribute: 'a', modifier: 121 }, { attribute: 'b', modifier: 67 }, { attribute: 'c', modifier: 121 }, { attribute: 'd', modifier: 67 } ]; let obj=array.reduce(function(obj,item){ obj[item.attribute] = item.modifier; return obj; },{}); console.log(obj); 

Answer 2

You could use Object.assign in combination with Array#map .

 var array = [{ attribute: 'a', modifier: 121 }, { attribute: 'b', modifier: 67 }, { attribute: 'c', modifier: 121 }, { attribute: 'd', modifier: 67 }], result = Object.assign(...array.map(o => ({ [o.attribute]: o.modifier }))); console.log(result); 

With destructuring assignment

 var array = [{ attribute: 'a', modifier: 121 }, { attribute: 'b', modifier: 67 }, { attribute: 'c', modifier: 121 }, { attribute: 'd', modifier: 67 }], result = Object.assign(...array.map(({ attribute, modifier }) => ({ [attribute]: modifier }))); console.log(result); 

Answer 3

try this.

 var arr = [ { attribute: 'a', modifier: 121 }, { attribute: 'b', modifier: 67 }, { attribute: 'c', modifier: 121 }, { attribute: 'd', modifier: 67 } ] var map = {}; arr.forEach( function(item){ map[ item.attribute ] = item.modifier }); console.log( JSON.stringify( map, 0, 4 ) )