exercise5.md

Exercise

Given a string and a value such as:

var str = "asdf[0][1][1].sss.ddd"
var value = 2

Create a function that when given an object and a key path, it assigns a value to the given key path such that:

var obj = {};
deepAssignment(obj, str, value)
obj.asdf[0][1][1].sss.ddd === 2

Also try to keep Array and Objects types:

Array.isArray(obj.asdf[0][1][1]) === true
isObject(obj.asdf[0][1][1]) === false
isObject(obj.asdf[0][1][1].sss) ==== true

Solution

function deepAssignment(obj, keyPath, value) {
  const keys = keyPath.split('.')
          .map(str => str.split('['))
          .reduce((prev, next) => prev = prev.concat(next), [])
          .map(val => {
            if(val.includes(']')){
              return { val: +(val.replace(']', '')), type: 'array' };
            }
            return { val: val, type: 'object' };
          });

  return keys.reduce((prev, curr, i, array) => {
    if(array[i + 1] && array[i + 1].type === 'object'){
      prev[curr.val] = prev[curr.val] || {};
      return prev[curr.val];
    } else if(array[i + 1] && array[i + 1].type === 'array'){
      prev[curr.val] = prev[curr.val] || []
      return prev[curr.val];
    } else {
       prev[curr.val] = value;
    }
    return prev;
  }, obj);
}