JavaScript遍历对象4种方法和遍历数组的3种方式 代码

//遍历对象 4种方法
//Object.keys(obj).forEach()
console.log("keys...遍历</br>")
var obj1 = {
    '0': 'a',
    '1': 'b',
    '2': 'c'
};
Object.keys(obj1).forEach(function (keys) {
    console.log(keys, obj1[keys]);
})

//for(var i in obj){}
console.log("For...in... ")
var obj2 = {
    '0': 'a',
    '1': 'b',
    '2': 'c'
};
for (var i in obj2) {
    console.log(i, obj2[i]);
}

//Object.getOwnPropertyNames(obj) 

console.log("Object.getOwnPropertyNames(obj)")
var obj3 = {
    '0': 'a',
    '1': 'b',
    '2': 'c'
};
Object.getOwnPropertyNames(obj3).forEach(function (keys) {
    console.log(keys, obj3[keys]);
})

//Reflect.ownKeys(obj).forEach   此乃es6新方法
console.log("Reflect.ownKeys(obj).forEach")
var obj4 = {
    '0': 'a',
    '1': 'b',
    '2': 'c'
};
Reflect.ownKeys(obj4).forEach(function (keys) {
    console.log(keys, obj4[keys]);
})

//遍历数组 3种方法
console.log("forEach")
var arr1 = [1, 2, 3, 4];

arr1.forEach(function (val, index) {
    console.log(val, index);
});

console.log("for...in...")
var arr2 = [1, 2, 3, 4];
for (let i in arr2) {
    console.log(i, arr2[i]);
}

console.log("for...of...")
var arr3 = [1, 2, 3, 4];
for (let value in arr3) {
    console.log(value);
}