2794-CreateObjectFromTwoArrays.js

// 2794. Create Object from Two Arrays
// Given two arrays keysArr and valuesArr, return a new object obj. 
// Each key-value pair in obj should come from keysArr[i] and valuesArr[i].
// If a duplicate key exists at a previous index, that key-value should be excluded. 
// In other words, only the first key should be added to the object.
// If the key is not a string, it should be converted into a string by calling String() on it.

// Example 1
// Input: keysArr = ["a", "b", "c"], valuesArr = [1, 2, 3]
// Output: {"a": 1, "b": 2, "c": 3}
// Explanation: The keys "a", "b", and "c" are paired with the values 1, 2, and 3 respectively.

// Example 2:
// Input: keysArr = ["1", 1, false], valuesArr = [4, 5, 6]
// Output: {"1": 4, "false": 6}
// Explanation: First, all the elements in keysArr are converted into strings. We can see there are two occurrences of "1". The value associated with the first occurrence of "1" is used: 4.

// Example 3:
// Input: keysArr = [], valuesArr = []
// Output: {}
// Explanation: There are no keys so an empty object is returned.
 
// Constraints:
//         keysArr and valuesArr are valid JSON arrays
//         2 <= JSON.stringify(keysArr).length, JSON.stringify(valuesArr).length <= 5 * 10^5
//         keysArr.length === valuesArr.length

/**
 * @param {Array} keysArr
 * @param {Array} valuesArr
 * @return {Object}
 */
var createObject = function(keysArr, valuesArr) {
    let res = {};
    for(let o in keysArr) {
        //let k = keysArr[o].toString(); // null 没有 toString方法
        let k = String(keysArr[o]);
        if (res[k] !== undefined) continue;
        res[k] = valuesArr[o];
    }
    return res;
};

var createObject1 = function(keysArr, valuesArr) {
    let obj = Object.create(null)
    keysArr.forEach((key, index) => {
        key = String(key)
        if (key in obj) return
        obj[key] = valuesArr[index]
    })
    return obj
  };


console.log(createObject(["a", "b", "c"],[1, 2, 3])) // {"a": 1, "b": 2, "c": 3}
console.log(createObject(["1", 1, false],[4, 5, 6])) // {"1": 4, "false": 6}
console.log(createObject([],[])) // {}

console.log(createObject1(["a", "b", "c"],[1, 2, 3])) // {"a": 1, "b": 2, "c": 3}
console.log(createObject1(["1", 1, false],[4, 5, 6])) // {"1": 4, "false": 6}
console.log(createObject1([],[])) // {}