是否需要声明函数变量(使用Javascript)? [英] Is declaring a function variable required (in Javascript)?

问题描述

我学校的老师在教我们，我们必须像这样专门声明函数变量:

 函数功能(var1，var2){var var1，var2;console.log(var1);console.log(var2);}东西(完全"，酷")； 

但是我似乎找不到任何与此相关的主题，所以我的问题是，这是否是必需的?只是将 var var1，var2; 留在外面不是很正常吗?

如果是，这是在W3C JavaScript文档中的某个地方说明的吗?

我的意思是无论哪种方式都可以工作，但是如果没有它就可以工作.

我正在谈论的代码: http://pastebin.com/y5B2aznc

谢谢！

解决方案

在您的特定情况下，所有作为参数传递的变量都是 local 变量，就像您使用 var .因此，使用 var 重新声明它们是多余的.

但是更好的做法是将参数保留其原始值，并对其进行处理以将结果存储在其他局部变量中.例如:

 函数功能(var1，var2){var varAlt1 = var1.toUpperCase()，varAlt2 = var2.toLowerCase();console.log(varAlt1);console.log(varAlt2);} 

The teachers at my school are teaching us we have to specifically declare function variables like so:

function something(var1, var2)
{
    var var1, var2;
    console.log(var1);
    console.log(var2);
}

something("Totally", "Cool");

However I can't seem to find any topics about this, so my question is, is this even required? Isn't it perfectly normal and OK to just leave the var var1, var2; out?

If so, is this stated somewhere in the W3C JavaScript documentation?

I mean it works either way, but if it works without... Cleaner code I'd say :P

Code I'm talking about: http://pastebin.com/y5B2aznc

Thanks!

解决方案

In your particular case, all the variables passed as arguments are local variables just like the variables you declare with var. So re-declaring them with var is redundant.

But a better practice is to leave the arguments with their original values, and do stuff with them storing the results in other local variables. E.g.:

function something(var1, var2)
{
    var varAlt1 = var1.toUpperCase(), varAlt2 = var2.toLowerCase();
    console.log(varAlt1);
    console.log(varAlt2);
}

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