关联数组对象上的JavaScript foreach循环

// Defining an array
var array = [];
// Assigning values to corresponding keys
array["Main"] = "Main page";
array["Guide"] = "Guide page";
array["Articles"] = "Articles page";
array["Forum"] = "Forum board";
// Expected: loop over every item,
// yet it logs only "last" assigned value - "Forum"
for (var i = 0; i < array.length; i++) {
    console.log(array[i]);
}

array['Main'] = 'Main Page';

array.Main = 'Main Page';

// Assigning values to corresponding keys
const pages = {
  Main: 'Main page',
  Guide: 'Guide page',
  Articles: 'Articles page',
  Forum: 'Forum board',
Object.keys(pages).forEach((page) => console.log(page));

var obj = {
  no: ["no", 32],
  nt: ["no", 32],
  nf: ["no", 32, 90]
count = -1; // Which must be a static value
for (i in obj) {
  count++;
  if (obj.hasOwnProperty(i)) {
    console.log(obj[i][count])
};

Object.prototype.forEach = function(cb){
   if(this instanceof Array) return this.forEach(cb);
   let self = this;
   Object.getOwnPropertyNames(this).forEach(
      (k)=>{ cb.call(self, self[k], k); }
Object({a:1,b:2,c:3}).forEach((value, key)=>{ 
    console.log(`key/value pair: ${key}/${value}`);
});

const h = {
  a: 1,
Object.entries(h).forEach(([key, value]) => console.log(value));
// logs 1, 2

var array = [];
array["Main"] = "Main page";

let map = new Map();
map.set("Main", "Main page");

for (const value of map.values()) {
    // Here, `value` will be `"Main page"`, etc.
}

let obj = Object.create(null); // Creates an object with no prototype
obj.Main = "Main page"; // Or: `obj["Main"] = "Main page";`

for (const value of Object.values(proches_X)) {
    // Here, `value` will be `"Main page"`, etc.
}

var array = [];
// Assigning values to corresponding keys
array[0] = "Main page";
array[1] = "Guide page";
array[2] = "Articles page";

关联数组对象上的JavaScript foreach循环

7 个回答