使用Object.create的propertyObject参数 代码语言:javascript 复制 varo;// create an object with null as prototypeo=Object.create(null);o={};// is equivalent to:o=Object.create(Object.prototype);// Example where we create an object with a couple of// sample properties. (Note that the second ...
1.3 Object.create()方法 JavaScript中的每个对象都将从主对象创建。任何时候使用大写字母“O”时,指的都是主对象。我们可以在console控制台中打印主对象。主对象有很多方法,下面来看object.create()方法。 Object.create()创建法使用现有对象作为原型来创建新对象。基本语法如下: Object.create(proto,[propertiesObject]...
In the above example, the keysrollNoandfacultydo not exist within the object. Hence, when we assign values to these keys, new properties are added to the object. 3. Delete Object Properties We can remove properties from an object using thedeleteoperator. For example, constemployee = {name:...
create: function (slots) {// create objectvar obj = Object.create(this.methods,this.properties);// add special property for *direct type* of objectObject.defineProperty( obj,"type", {value:this, writable:false, enumerable:true});// initialize objectObject.keys( slots).forEach( function (pr...
Object.defineProperty(obj,"subtract", { set :function(i) {this.counter-= i;} }); // Play with the counter: obj.reset; obj.add=5; obj.subtract=1; obj.increment; obj.decrement; Try it Yourself » Prototype Properties JavaScript objects inherit the properties of their prototype. ...
function fn() { "use strict"; fn.arguments; // 报错 fn.caller; // 报错 // Uncaught TypeError: 'caller', 'callee', and 'arguments' properties may not be accessed on strict mode functions or the arguments objects for calls to them}fn();4. 禁止删除变量 严格模式下无法删除变量。"...
A JavaScript object is a collection ofnamed values. The following example creates a JavaScript object with four key/value properties: Example constperson = { firstName:"John", lastName:"Doe", age:50, eyeColor:"blue" }; Try it Yourself » ...
// create object from Animal prototype let snake = Object.create(Animal); snake.makeSound(); // Unspecified // properties can be created and overridden snake.sound = "Hiss"; snake.makeSound(); // Hiss // can also directly initialize object properties with second argument let properties = ...
The names of the properties and their values tellObject.defineProperties what properties to create or change on obj. Example: 1 2 3 4 var obj = Object.defineProperties({}, { foo: { value: 123, enumerable: true }, bar: { value: "abc", enumerable: true } }); Object.create(proto,...
with 关键字 with关键字用作引用对象的属性或方法的一种简写形式。 指定为with的参数的对象将在随后的块持续时间内成为默认对象,可以使用该对象的属性和方法而无需命名该对象。 with(object){properties used without theobjectnameanddot} 请尝试以下示例。