Javascript '；这'；关键字内置函数

我不太明白内置函数中的'this'关键字（如String、Number等）如何直接指向基元值，而不是像'this'关键字那样的对象。它只是由javascript引擎直接设置的吗

我举了一个例子：

String.prototype.repeatify = function(times) {
    console.log(this);   // Output - String {"hello"}
    var str = "";
    for(var i=0; i<times; i++) {
        str += this;     //how does 'this' gets set to 'hello' and not the object- String{  }??
    }
    return str;
}
var string = new String('hello');
console.log(string.repeatify(3));   //Output - prints hellohellohello

String.prototype.repeatify=函数（次）{
log（this）；//输出-字符串{“hello”}
var str=“”；
对于（var i=0；i
您在字符串原型上定义了
repeatify
，因此这只是一种字符串类型。因此，它将记录
hellohello
，
这有很多内容，但它本质上是函数调用的目标

一些例子：

String.prototype.whatever = function() {
  return this + ' ugh.. whatever.'
  // `this` is the string this method is called against
}

Array.prototype.slip = function() {
  return ['Hellooo', ...this];
  // `this` is the array in which the function is invoked on
}

function doSomething() {
  console.log(this + ' something');
  // `this` is whatever the function is bound to
}

console.log('Excuse me'.whatever()) // Excuse me ugh.. whatever.
console.log([1, 2, 3].slip()) // ["Hellooo", 1, 2, 3]

// In this case, the string 'I will do' becomes `this` in the doSomething function above as it's explicitly bound
doSomething.bind('I will do')(); // I will do something

此
是函数的当前范围，当您在
字符串
类型上运行它时，
此
是字符串本身
此
不是
对象{}
或
字符串{}
内置函数？？？@roanshaz为什么您认为
此
应该是
[对象对象]
因为这正是您所期望的。@KarelG我认为“this”总是绑定到创建它的对象上（意思是“this”指向
字符串{}
对象这与
this
几乎没有关系，所有这些都与基本类型的隐式（un）有关装箱到对象/从对象以及
+
运算符如何隐式获取对象的基本值。现在，这看起来可能是一条注释（重复项比这个答案更具解释性），因此在
String.prototype.whatever=function（）中{返回this+'ugh..which.'/'this'是调用此方法所针对的字符串}
如何获取此字符串的长度？？？
this
是字符串，因此
this.length
String.prototype.whatever = function() {
  return this + ' ugh.. whatever.'
  // `this` is the string this method is called against
}

Array.prototype.slip = function() {
  return ['Hellooo', ...this];
  // `this` is the array in which the function is invoked on
}

function doSomething() {
  console.log(this + ' something');
  // `this` is whatever the function is bound to
}

console.log('Excuse me'.whatever()) // Excuse me ugh.. whatever.
console.log([1, 2, 3].slip()) // ["Hellooo", 1, 2, 3]

// In this case, the string 'I will do' becomes `this` in the doSomething function above as it's explicitly bound
doSomething.bind('I will do')(); // I will do something