JavaScript 分配自变量

Question

这是如何工作的:

function Test() {
    this.t=function() {
        var self=this;
        self.tutu = 15;
        console.log(self);
    }
}
var olivier = new Test();

这有效:

function Test() {
    this.t=function() {
        var self  = this,
            other = -1;
        self.tutu = 15;
        console.log(self);
    }
}
var olivier = new Test();

这不起作用(出现错误SyntaxError:意外的标记。):

function Test() {
    this.t=function() {
        var self  = this,
            other = -1,
            self.tutu = 15;
        console.log(self);
    }
}
var olivier = new Test();

Answer 1

var语句用于声明变量。因此，您尝试定义一个名为 self.tutu 的变量，这在 JavaScript 中是无效的，因为变量名称中不应包含 . 。这就是它因语法错误而失败的原因。

SyntaxError: Unexpected token .

引用自Variables section in MDN ,

A JavaScript identifier must start with a letter, underscore (_), or dollar sign ($); subsequent characters can also be digits (0-9). Because JavaScript is case sensitive, letters include the characters "A" through "Z" (uppercase) and the characters "a" through "z" (lowercase).

Starting with JavaScript 1.5, you can use ISO 8859-1 or Unicode letters such as å and ü in identifiers. You can also use the \uXXXX Unicode escape sequences as characters in identifiers.