[英]Difference between node.js and chrome in v8
chrome version 49.0.2623.110 m 铬版本49.0.2623.110米
node v5.10.0 节点v5.10.0
Here is my code: 这是我的代码:
var a = 0;
(function() {
this.a = 1;
this.b = 2;
console.log(a);
} )();
console.log(a);
console.log(b);
chrome gives 铬给
1
1
2
node gives 节点给出
0
0
2
Why does that happen? 为什么会这样?
Thanks 谢谢
When a function is called without context (and you are running in non-strict mode) this
defaults to the global object. 如果在没有上下文的情况下调用函数(并且您在非严格模式下运行), this
默认为全局对象。
In a browser the top-level of your source code runs in the global context, so this.a
, which is window.a
is the same as the var a
declared in the global context at the top. 在浏览器中,源代码的顶层在全局上下文中运行,因此this.a
( window.a
)与在顶部的全局上下文中声明的var a
相同。 Assigning this.a = 1
is the same as assigning a = 1
. 分配this.a = 1
与分配a = 1
相同。
In node.js each JavaScript file gets its own module context that is separate from the global context, so var a = 0;
在node.js中,每个JavaScript文件都有自己的模块上下文,它与全局上下文分开,因此var a = 0;
is not creating a global, and the global you created with this.a = 1;
没有创建一个全局,以及你用this.a = 1;
创建的全局this.a = 1;
will be shadowed by the modules own a
. 将被模块拥有a
阴影。
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