Change key name in JavaScript object

Question

I am checking the attributes in a JavaScript object, replacing some of the keys by deleting the prefix \"element\" and saving the new values in another object.

Answer 1

We'll write a little function to fix the key the way you want.

function fix_key(key) { return key.replace(/^element_/, ''); }

Underscore

_.object(
  _.map(_.keys(json), fix_key),
  _.values(json)
)

ES5/loop

var keys = Object.keys(json);
var result = {};

for (i = 0; i < keys.length; i++) {
  var key = keys[i];
  result[fix_key(key)] = json[key];
}

return result;

ES5/reduce

Object.keys(json) . reduce(function(result, key) {
  result[fix_key(key)] = json[key];
  return result;
}, {});

ES6

Object.assign(
  {},
  ...Object.keys(json) .
    map(key => ({[fix_key(key)]: json[key]}))
)

This makes an array of little objects each with one key-value pair, using the ES6 "computed property name" feature, then passes them to Object.assign using the ES6 "spread" operator, which merges them together.