19.对象方法扩展

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对象方法扩展

(1) Object.is()

Object.is 比较两个值是否严格相等，与『===』行为基本一致

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// 1. Object.is() 判断两个值是否完全相等
console.log(Object.is(120, 120));   // true
console.log(Object.is(NaN, NaN));   // true
console.log(NaN === NaN);           // false

(2) Object.assign()

Object.assign(obj_source, obj_target) 对象的合并，将源对象的所有可枚举属性，复制到目标对象

Object.assign(obj_1, obj_2): 用 obj_2 去合并覆盖 obj_1，返回合并后的结果，同时 obj_1 的值会被修改，变为合并后的结果

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// 2. Object.assign() 对象的合并
const config1 = {
    ip: '192.168.100.10',
    port: 3306,
    password: '123456'
};
const config2 = {
    username: 'root',
    password: 'abcdef'
}
const mergeConfig = Object.assign(config1, config2);
console.log(mergeConfig);   // {ip: '192.168.100.10', port: 3306, password: 'abcdef', username: 'root'}
console.log(config1);       // {ip: '192.168.100.10', port: 3306, password: 'abcdef', username: 'root'}
console.log(config2);       // {username: 'root', password: 'abcdef'}

(3) Object.setPrototypeOf() 和 Object.getPrototypeof()

  • Object.setPrototypeOf(obj_1, obj_2): 设置原型对象，设置 obj_1 的原型为 obj_2
  • Object.getPrototypeof(obj): 获取原型对象
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// 3. Object.setPrototypeOf() 和 Object.getPrototypeof()
const school = {
    name: 'university'
}
const district = {
    city: ['London','Paris','Boston']
}
Object.setPrototypeOf(school, district);

console.log(Object.getPrototypeOf(school));
/**
 * {city: Array(3)}
 *      city: (3) ['London', 'Paris', 'Boston']
 *      [[Prototype]]: Object
 */

console.log(school);
/**
 * {name: 'university'}
 *      name: "university"
 *      [[Prototype]]: Object
 *          city: (3) ['London', 'Paris', 'Boston']
 *          [[Prototype]]: Object
 */