javascript - 嵌套函数无法识别 javascript "this"关键字

Question

我无法让我的嵌套函数识别“this”关键字。这是一个例子。我有一个构造函数:

function person(first, last, age, eyecolor) {
    this.firstName = first;
    this.lastName = last;
    this.age = age;
    this.changeName = changename;
}

我有另一个带有嵌套函数的函数:

function changeName (name) {
     this.lastname = name;
     $.post("display.php", "some_data", function(data,status) {
        if (status=="success") {
               alert(this.lastName); //undefined
        }
     }

}

Answer 1

该函数从您需要使用 .bind 或“hack”的内部函数设置此值:

function changeName (name) {

     var that = this;

     this.lastname = name;
     $.post("display.php", "some_data", function(data,status) {
        if (status=="success") {
               alert(that.lastName); //undefined
        }
     }
}

或者使用function.protoype.bind .

function changeName (name) {

     this.lastname = name;
     $.post("display.php", "some_data", function(data,status) {
        if (status=="success") {
               alert(this.lastName); //undefined
        }
     }.bind(this))
}

这是一个相当不错的explanation