之前的文章《一文讲解Vue中路由切换终止异步请求(附代码)》中,给大家介绍了解了vue中路由切换终止异步请求。下面本篇文章给大家了解js中Reflect内置对象,有一定的参考价值,有需要的朋友可以参考一下,希望对你 ...
语义
描述与大多数全局对象不同, 兼容性Chrome:49+ Firefox (Gecko):42+ 其他浏览器暂未实现 句法
参数
目标函数。
函数调用时绑定的
target函数调用时传入的实参列表,该参数应该是一个类数组的对象。 方法Reflect.apply()
静态方法 Reflect.apply(Math.floor, undefined, [1.75]); // 1; Reflect.apply(String.fromCharCode, undefined, [104, 101, 108, 108, 111]); // "hello" Reflect.apply(RegExp.prototype.exec, /ab/, ["confabulation"]).index; // 4 Reflect.apply("".charAt, "ponies", [3]); // "i" Reflect.construct()
var d = Reflect.construct(Date, [1776, 6, 4]); d instanceof Date; // true d.getFullYear(); // 1776 Reflect.defineProperty()
const object1 = {}; if (Reflect.defineProperty(object1, "property1", { value: 42 })) { console.log("property1 created!"); // expected output: "property1 created!" } else { console.log("problem creating property1"); } console.log(object1.property1); // expected output: 42 Reflect.deleteProperty() 静态方法
var obj = { x: 1, y: 2 }; Reflect.deleteProperty(obj, "x"); // true obj; // { y: 2 } var arr = [1, 2, 3, 4, 5]; Reflect.deleteProperty(arr, "3"); // true arr; // [1, 2, 3, , 5] // 如果属性不存在,返回 true Reflect.deleteProperty({}, "foo"); // true // 如果属性不可配置,返回 false Reflect.deleteProperty(Object.freeze({ foo: 1 }), "foo"); // false Reflect.get()
// Object var obj = { x: 1, y: 2 }; Reflect.get(obj, "x"); // 1 // Array Reflect.get(["zero", "one"], 1); // "one" // Proxy with a get handler var x = { p: 1 }; var obj = new Proxy(x, { get(t, k, r) { return k + "bar"; }, }); Reflect.get(obj, "foo"); // "foobar" Reflect.getOwnPropertyDescriptor() 静态方法
Reflect.getOwnPropertyDescriptor({ x: "hello" }, "x"); // {value: "hello", writable: true, enumerable: true, configurable: true} Reflect.getOwnPropertyDescriptor({ x: "hello" }, "y"); // undefined Reflect.getOwnPropertyDescriptor([], "length"); // {value: 0, writable: true, enumerable: false, configurable: false} Reflect.getPrototypeOf() 静态方法
Reflect.getPrototypeOf({}); // Object.prototype Reflect.getPrototypeOf(Object.prototype); // null Reflect.getPrototypeOf(Object.create(null)); // null Reflect.has() 静态方法
Reflect.has({ x: 0 }, "x"); // true Reflect.has({ x: 0 }, "y"); // false // 如果该属性存在于原型链中,返回true Reflect.has({ x: 0 }, "toString"); // Proxy 对象的 .has() 句柄方法 obj = new Proxy( {}, { has(t, k) { return k.startsWith("door"); }, } ); Reflect.has(obj, "doorbell"); // true Reflect.has(obj, "dormitory"); // false Reflect.isExtensible() 静态方法 Reflect.isExtensible(target) // New objects are extensible. var empty = {}; Reflect.isExtensible(empty); // === true // ...but that can be changed. Reflect.preventExtensions(empty); Reflect.isExtensible(empty); // === false // Sealed objects are by definition non-extensible. var sealed = Object.seal({}); Reflect.isExtensible(sealed); // === false // Frozen objects are also by definition non-extensible. var frozen = Object.freeze({}); Reflect.isExtensible(frozen); // === false //diff Object.isExtensible Reflect.isExtensible(1); // TypeError: 1 is not an object Object.isExtensible(1); // false Reflect.ownKeys() 静态方法
const object1 = { property1: 42, property2: 13, }; var array1 = []; console.log(Reflect.ownKeys(object1)); // expected output: Array ["property1", "property2"] console.log(Reflect.ownKeys(array1)); // expected output: Array ["length"] Reflect.ownKeys({ z: 3, y: 2, x: 1 }); // [ "z", "y", "x" ] Reflect.ownKeys([]); // ["length"] var sym = Symbol.for("comet"); var sym2 = Symbol.for("meteor"); var obj = { [sym]: 0, str: 0, "773": 0, "0": 0, [sym2]: 0, "-1": 0, "8": 0, "second str": 0, }; Reflect.ownKeys(obj); // [ "0", "8", "773", "str", "-1", "second str", Symbol(comet), Symbol(meteor) ] // Indexes in numeric order, // strings in insertion order, // symbols in insertion order Reflect.preventExtensions() 静态方法
// Objects are extensible by default. var empty = {}; Reflect.isExtensible(empty); // === true // ...but that can be changed. Reflect.preventExtensions(empty); Reflect.isExtensible(empty); // === false //diff Object.preventExtensions() Reflect.preventExtensions(1); // TypeError: 1 is not an object Object.preventExtensions(1); // 1 Reflect.set() 静态方法
// Object var obj = {}; Reflect.set(obj, "prop", "value"); // true obj.prop; // "value" // Array var arr = ["duck", "duck", "duck"]; Reflect.set(arr, 2, "goose"); // true arr[2]; // "goose" // It can truncate an array. Reflect.set(arr, "length", 1); // true arr; // ["duck"]; // With just one argument, propertyKey and value are "undefined". var obj = {}; Reflect.set(obj); // true Reflect.getOwnPropertyDescriptor(obj, "undefined"); // { value: undefined, writable: true, enumerable: true, configurable: true } Reflect.setPrototypeOf() 静态方法
Reflect.setPrototypeOf({}, Object.prototype); // true // It can change an object's [[Prototype]] to null. Reflect.setPrototypeOf({}, null); // true // Returns false if target is not extensible. Reflect.setPrototypeOf(Object.freeze({}), null); // false // Returns false if it cause a prototype chain cycle. var target = {}; var proto = Object.create(target); Reflect.setPrototypeOf(target, proto); // false 推荐学习:JavaScript视频教程 以上就是浅析javascript中Reflect内置对象(代码详解)的详细内容,更多请关注模板之家(www.mb5.com.cn)其它相关文章! |