I'd like to know what's happening in the line's I've bolded. I know they 'work, ' but I'm not sure why.

See more:

Javascript

I was doing in exercise in which I had to write a function called select. Given an array and object, I had to return a new object whose properties included only those which were common among the array and the original object. For example:

var arr = ['a', 'c', 'e'];
var obj = {
  a: 1,
  b: 2,
  c: 3,
  d: 4
};
var output = select(arr, obj);
console.log(output); // --> { a: 1, c: 3 }

The code below 'works,' but I'm trying to understand how newObject[search] = obj[search] yields the right results in newObject.

function select(arr, obj) {
  var newObject = {};
  var keys = Object.keys(obj);
  for (var i = 0; i < arr.length; i++) {
    var search = arr[i];
      if (keys.indexOf(search) !== - 1) {
        newObject[search] = obj[search];
    }
  }
  return newObject;
}

What I have tried:

I've run this code through the debugger in Google dev tools multiple times. My best understanding is that obj[search] reaches all the way back up to the 'keys' variable to find out how it relates to the 'search' variable.

Thanks sincerely for your help!