浏览器和节点之间有什么区别？

what's the difference between Browsers and Node? for instance:

浏览器和节点之间有什么区别?例如:

setName.js on Node:

节点上的setName.js:

var setName;
setName = function (name) {
    return this.name = name;
};
setName("LuLu");
//LuLu
console.log(name);
//undefined
console.log(this.name);

setName.html in browser:

浏览器中的setName.html:

<script>
    var setName;
    setName = function (name) {
        return this.name = name;
    };
    setName("LuLu");
    //LuLu
    console.log(name);
    //LuLu
    console.log(this.name);
</script>

the the second log is different,why?

第二个日志不同,为什么?

2 个解决方案

#1

Node is a JavaScript engine, not a browser. The specific reason that you see undefined in Node, and Lulu in a browser? Differences in the global namespace:

Node是JavaScript引擎,而不是浏览器。您在Node中看到未定义的特定原因,以及浏览器中的Lulu?全局命名空间的差异:

In browsers, the top-level scope is the global scope. That means that in browsers if you're in the global scope var something will define a global variable. In Node this is different. The top-level scope is not the global scope; var something inside a Node module will be local to that module.

在浏览器中,*范围是全局范围。这意味着在浏览器中,如果您处于全局范围,则var将定义全局变量。在Node中,这是不同的。*范围不是全球范围; Node模块中的var内容将是该模块的本地内容。

In the browser, this is a reference to the window object — the browser's global namespace — for all functions which are invoked unattached to an object (e.g. not like foo.bar()). In Node, this is simply not a reference to the global namespace.

在浏览器中,这是对窗口对象(浏览器的全局命名空间)的引用,用于所有未附加到对象的函数(例如,不像foo.bar())。在Node中,这不是对全局命名空间的引用。

N.B. console.log(this.name) in a Node interpreter will print Lulu, not undefined. That's because, in the REPL only,

注:节点解释器中的console.log(this.name)将打印Lulu,而不是未定义。那是因为,仅在REPL中,

> this === global
true

Further reading @ How To Node: What is "this?"

进一步阅读@如何节点:什么是“这个?”

Okay, one more edit as prompted by @Šime Vidas' comment regarding this in ES5 strict mode:

好的,在ŠimeVidas关于ES5严格模式的评论提示的另一个编辑:

In the global context (outside of any function), this refers to the global object, whether in strict mode or not.

在全局上下文中(在任何函数之外),这指的是全局对象,无论是否处于严格模式。

When the this keyword occurs inside a function, its value depends on how the function is called.

当this关键字出现在函数内部时,其值取决于函数的调用方式。

When a function is called as a method of an object, its this is set to the object the method is called on.

当一个函数作为一个对象的方法被调用时,它被设置为调用该方法的对象。

More interesting reading courtesy of Juriy Zaytsev (aka @kangax) in one of his blog posts.

更有趣的阅读由Juriy Zaytsev(又名@kangax)在他的一篇博客文章中提供。

#2

Your browser code has the window host object. Node does not have that host object. When you set this.name, you are actually setting it to the window object aka making a global variable.

您的浏览器代码具有窗口主机对象。节点没有该主机对象。设置this.name时,实际上是将其设置为窗口对象,即创建全局变量。

window.name === this.name // true

window.name === this.name // true

#1