遍历对象的可枚举属性

// 遍历对象的可枚举属性
var obj = {
name:'Nicholas',
job:'engineer'
};
Object.getPrototypeOf(obj).age = 33;

//1.for-in
for (var property in obj) {
console.log('Name:' + property);
console.log('Value:' + obj[property]);
}

//2.Object.keys()
var properties = Object.keys(obj);
var i,len;
for (var i = 0; i < properties.length; i++) {
console.log('Name:' + properties[i]);
console.log('Value:' + obj[properties[i]]);
}

// 区别：for-in会遍历原型属性而Object.keys()只返回自有（实例）属性。

// 对for-in进行以下处理，则for-in等同于Object.keys()
for (var property in obj) {
if(obj.hasOwnProperty(property)) {
console.log('Name:' + property);
console.log('Value:' + obj[property]);
}
}