JavaScript: Convert array of objects into hashmap

Question

I have a set of values in an array where each value has an ID and LABEL.

Once I have the value array and type console value[0] and value[1], the output is:

value[0] 
Object {ID: 0, LABEL: turbo}

value[1] 
Object {ID: 1, LABEL: classic}

How can I store these values in a hash map like a key-value (ID-LABEL) pair, and store them in a json?

Answer 1

This could be achieved by calling reduce on your array of values (ie data), to obtain the required hash map (where ID is the key and value is the corresponding LABEL):

const data = [
{ID: 0, LABEL: 'turbo'},
{ID: 1, LABEL: 'classic'},
{ID: 7, LABEL: 'unknown'}
];

const hashMap = data.reduce((result, item) => {
  return { ...result, [ item.ID ] : item.LABEL };
}, {});

const hashMapJson = JSON.stringify(hashMap);

console.log('hashMap', hashMap);
console.log('hashMapJson', hashMapJson);
 
/*
More concise syntax:
console.log(data.reduce((result, { ID, LABEL }) => ({ ...result, [ ID ] : LABEL }), {}))
*/