javascript 如何在javascript中打印函数签名
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How to Print Function Signature in javascript
提问by Ashish Negi
I have a function:
我有一个功能：
fs.readFile = function(filename, callback) {
// implementation code.
};
Sometime later I want to see the signature of the function during debugging.
稍后我想在调试期间查看函数的签名。
When I tried console.log(fs.readFile)I get [ FUNCTION ].
当我尝试时，console.log(fs.readFile)我得到[ FUNCTION ].
That does not give me any information.
那没有给我任何信息。
How can I get the signature of the function?
我怎样才能得到函数的签名？
回答by georg
In node.js specifically, you have to convert the function to string before logging:
特别是在 node.js 中，您必须在记录之前将函数转换为字符串：
$ node
> foo = function(bar, baz) { /* codez */ }
[Function]
> console.log(foo)
[Function]
undefined
> console.log(foo.toString())
function (bar, baz) { /* codez */ }
undefined
>
or use a shortcut like foo+""
或使用快捷方式 foo+""
回答by Andreas Hultgren
If what you mean by "function signature" is how many arguments it has defined, you can use:
如果“函数签名”的意思是它定义了多少个参数，则可以使用：
function fn (one) {}
console.log(fn.length); // 1
All functions get a length property automatically.
所有函数都会自动获得一个长度属性。
回答by ???? ???p
I am not sure what you want but try looking at the console log of this fiddle, it prints entire function definition. I am looking at chrome console.log output.
我不确定你想要什么，但尝试查看这个小提琴的控制台日志，它打印了整个函数定义。我正在查看 chrome console.log 输出。
var fs = fs || {};
fs.readFile = function(filename, callback) {
alert(1);
};
console.log(fs.readFile);
