constnumbers={numberA:5,numberB:10,sum:function(){console.log(this===numbers);// => truefunctioncalculate(){console.log(this===numbers);// => truereturnthis.numberA+this.numberB;}// use .call() method to modify the contextreturncalculate.call(this);}};numbers.sum();// => 15 cal...
num; } }; // method invocation. this is calc calc.increment(); // => 1 calc.increment(); // => 2 通过方法调用的方式 calc.increment(),使得 increment 内部的 this 指向了 cals 对象,因此 this.num 会成功增加 num 属性的值。 让我们再看一个例子。对象通过原型继承一个方法,当方法通过属性...
call call() provides a new value ofthisto the function/method. Withcall(), you can write a method once and then inherit it in another object, without having to rewrite the method for the new object. call() //在不严格模式下默认绑定到global,在严格模式下会报错 call(thisArg) call(thisArg,...
在js中有一种所谓沙盒模型"boxing" mechanism. 这个盒子在进入被调用函数执行上下文之前将包裹或者变更this object.在匿名函数中,由于在strict mode下并未以obj.method方式来调用匿名函数,因此this就为undefined(原因是匿名函数就是一个闭包,其作用就是隔离了global scope,因此不会默认到window.method上去).而在非strict...
As an object method When a function is called as a method of an object, its this is set to the object the method is called on. 当函数作为对象的方法被调用时,它的this值就是该对象。 1 2 3 4 5 6 7 varcircle = { radius: 10, ...
method in object 我们知道,在对象里的值如果是原生值(primitive type;例如,字串、数值、逻辑值),我们会把这个新建立的东西称为「属性(property)」;如果对象里面的值是函数(function)的话,我们则会把这个新建立的东西称为「方法(method)」。 在这里,我们就要来建立method: ...
On browsers, this is always set to Window in a simple function. The same is true even if you call a simple function in an object method. function simpleFunction() { console.log(this) } const o = { sayThis() { simpleFunction() }, } simpleFunction() // Window o.sayThis() // Wi...
In the above example,thisrefers to thepersonobject. 5. this Inside Inner Function When you accessthisinside an inner function (inside a method),thisrefers to the global object. For example, constperson = {name:'Jack',age:25,// this inside method// this refers to the object itselfgreet(...
In an object method,thisrefers to theobject. Alone,thisrefers to theglobal object. In a function,thisrefers to theglobal object. In a function, in strict mode,thisisundefined. In an event,thisrefers to theelementthat received the event. ...
varheroIdentity='[Function Version]Iron Man';functioncheckIdentity(){returnthis.heroIdentity;}varobj={name:'Tony Stark',heroIdentity:'[Method Version]Iron Man',checkIdentityFromObj:checkIdentity}functionTheAvenger(name){this.heroIdentity=name;this.checkIdentityFromNew=checkIdentity;}vartony=newTheAveng...