Chrome / Firefox控制台.log总是附加一行说undefined [英] Chrome/Firefox console.log always appends a line saying undefined

问题描述

每次执行 console.log 时，会在输出日志中添加一行 undefined 。

解决方案

如果在Windows和Linux上使用Firefox和Chrome，你从一个JS文件运行 console.log（），这个 undefined 行不应该被追加。 p>

如果你从控制台运行 console.log（），这是有道理的。这是为什么：在控制台中，您可以键入变量的名称（例如尝试键入 window ），并打印有关它的信息。当您从控制台运行任何void函数（如console.log）时，它还会打印有关返回值的信息， undefined 。

我在我的Chrome（Mac版本23.0.1271.101）上测试了这两种情况，当我在控制台中运行时，我看到了 undefined 。这个 undefined 也出现在我在控制台写这行： var bla =sdfdfs

Every time console.log is executed, a line saying undefined is appended to the output log.

Happens in both Firefox and Chrome on Windows and Linux.

解决方案

If you're running console.log() from a JS file, this undefined line should not be appended.

If you're running console.log() from the console itself, it makes sense. This is why: In the console you can type a name of a variable (for example try typing window) and it prints info about it. When you run any void function (like console.log) from the console, it also prints out info about the return value, undefined in this case.

I tested both cases on my Chrome (Mac ver 23.0.1271.101) and indeed I see the undefined line when I run it inside the console. This undefined also appears when I write this line in the console: var bla = "sdfdfs"

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