Chrome/Firefox console.log 总是附加一行说“未定义" [英] Chrome/Firefox console.log always appends a line saying 'undefined'
问题描述
每次执行 console.log
时,都会在输出日志中附加一行表示 undefined
.
Every time console.log
is executed, a line saying undefined
is appended to the output log.
它发生在 Windows 和 Linux 上的 Firefox 和 Chrome 中.
It happens in both Firefox and Chrome on Windows and Linux.
推荐答案
如果你从 JS 文件运行 console.log()
,这行 undefined
应该不附加.
If you're running console.log()
from a JS file, this undefined
line should not be appended.
如果您从控制台本身运行 console.log()
,这是有道理的.这就是为什么: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,它还会打印出有关返回值的信息,在本例中为 undefined
.
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.
我在 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它时,确实看到了 undefined
行.这个 undefined
在我在控制台中写下这一行时也会出现:var bla = "sdfdfs"
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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