你可以使用"arguments"属性访问传递给函数的参数值。

    function doSomething()
    {
        var args = doSomething.arguments;
        var numArgs = args.length;
        for(var i = 0 ; i < numArgs ; i++)
        {
            console.log("arg " + (i+1) + " = " + args[i]);  
                    //console.log works with firefox + firebug
                    // you can use an alert to check in other browsers
        }
    }

    doSomething(1, '2', {A:2}, [1,2,3]);    

哇，已经有这么多答案了。我很确定这件事会被埋葬。即便如此，我觉得这对一些人来说可能有用。

我对所选的答案并不完全满意，因为在ES6中，默认值不能很好地工作。它也不提供默认值信息。我还想要一个不依赖于外部库的轻量级函数。

这个函数对于调试非常有用，例如:记录被调用函数的参数、默认参数值和参数。

我昨天花了一些时间在这个问题上，破解正确的RegExp来解决这个问题，这就是我想到的。它运行得非常好，我对结果非常满意:

const REGEX_COMMENTS = /((\/\/.*$)|(\/\*[\s\S]*?\*\/))/mg; const REGEX_FUNCTION_PARAMS = /(?:\s*(?:function\s*[^(]*)?\s*)((?:[^'"]|(?:(?:(['"])(?:(?:.*?[^\\]\2)|\2))))*?)\s*(?=(?:=>)|{)/m const REGEX_PARAMETERS_VALUES = /\s*(\w+)\s*(?:=\s*((?:(?:(['"])(?:\3|(?:.*?[^\\]\3)))((\s*\+\s*)(?:(?:(['"])(?:\6|(?:.*?[^\\]\6)))|(?:[\w$]*)))*)|.*?))?\s*(?:,|$)/gm /** * Retrieve a function's parameter names and default values * Notes: * - parameters with default values will not show up in transpiler code (Babel) because the parameter is removed from the function. * - does NOT support inline arrow functions as default values * to clarify: ( name = "string", add = defaultAddFunction ) - is ok * ( name = "string", add = ( a )=> a + 1 ) - is NOT ok * - does NOT support default string value that are appended with a non-standard ( word characters or $ ) variable name * to clarify: ( name = "string" + b ) - is ok * ( name = "string" + $b ) - is ok * ( name = "string" + b + "!" ) - is ok * ( name = "string" + λ ) - is NOT ok * @param {function} func * @returns {Array} - An array of the given function's parameter [key, default value] pairs. */ function getParams(func) { let functionAsString = func.toString() let params = [] let match functionAsString = functionAsString.replace(REGEX_COMMENTS, '') functionAsString = functionAsString.match(REGEX_FUNCTION_PARAMS)[1] if (functionAsString.charAt(0) === '(') functionAsString = functionAsString.slice(1, -1) while (match = REGEX_PARAMETERS_VALUES.exec(functionAsString)) params.push([match[1], match[2]]) return params } // Lets run some tests! var defaultName = 'some name' function test1(param1, param2, param3) { return (param1) => param1 + param2 + param3 } function test2(param1, param2 = 4 * (5 / 3), param3) {} function test3(param1, param2 = "/root/" + defaultName + ".jpeg", param3) {} function test4(param1, param2 = (a) => a + 1) {} console.log(getParams(test1)) console.log(getParams(test2)) console.log(getParams(test3)) console.log(getParams(test4)) // [ [ 'param1', undefined ], [ 'param2', undefined ], [ 'param3', undefined ] ] // [ [ 'param1', undefined ], [ 'param2', '4 * (5 / 3)' ], [ 'param3', undefined ] ] // [ [ 'param1', undefined ], [ 'param2', '"/root/" + defaultName + ".jpeg"' ], [ 'param3', undefined ] ] // [ [ 'param1', undefined ], [ 'param2', '( a' ] ] // --> This last one fails because of the inlined arrow function! var arrowTest1 = (a = 1) => a + 4 var arrowTest2 = a => b => a + b var arrowTest3 = (param1 = "/" + defaultName) => { return param1 + '...' } var arrowTest4 = (param1 = "/" + defaultName, param2 = 4, param3 = null) => { () => param3 ? param3 : param2 } console.log(getParams(arrowTest1)) console.log(getParams(arrowTest2)) console.log(getParams(arrowTest3)) console.log(getParams(arrowTest4)) // [ [ 'a', '1' ] ] // [ [ 'a', undefined ] ] // [ [ 'param1', '"/" + defaultName' ] ] // [ [ 'param1', '"/" + defaultName' ], [ 'param2', '4' ], [ 'param3', 'null' ] ] console.log(getParams((param1) => param1 + 1)) console.log(getParams((param1 = 'default') => { return param1 + '.jpeg' })) // [ [ 'param1', undefined ] ] // [ [ 'param1', '\'default\'' ] ]

正如你所知道的，一些参数名消失了，因为Babel转译器将它们从函数中删除了。如果你在最新的NodeJS中运行它，它会像预期的那样工作(注释的结果来自NodeJS)。

另一个注意事项，正如注释中所述，它不能作为默认值与内联箭头函数一起工作。这使得使用RegExp提取值变得非常复杂。

如果这对你有用，请让我知道!很乐意听到一些反馈!

这里有一种方法:

// Utility function to extract arg name-value pairs
function getArgs(args) {
    var argsObj = {};

    var argList = /\(([^)]*)/.exec(args.callee)[1];
    var argCnt = 0;
    var tokens;
    var argRe = /\s*([^,]+)/g;

    while (tokens = argRe.exec(argList)) {
        argsObj[tokens[1]] = args[argCnt++];
    }

    return argsObj;
}

// Test subject
function add(number1, number2) {
    var args = getArgs(arguments);
    console.log(args); // ({ number1: 3, number2: 4 })
}

// Invoke test subject
add(3, 4);

注意:这只适用于支持arguments.callee的浏览器。

这很简单。

At the first there is a deprecated arguments.callee — a reference to called function. At the second if you have a reference to your function you can easily get their textual representation. At the third if you calling your function as constructor you can also have a link via yourObject.constructor. NB: The first solution deprecated so if you can't to not use it you must also think about your app architecture. If you don't need exact variable names just use inside a function internal variable arguments without any magic.

https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Functions_and_function_scope/arguments/callee

它们都将调用toString并将其替换为re，这样我们就可以创建一个helper:

// getting names of declared parameters
var getFunctionParams = function (func) {
    return String(func).replace(/[^\(]+\(([^\)]*)\).*/m, '$1');
}

一些例子:

// Solution 1. deprecated! don't use it!
var myPrivateFunction = function SomeFuncName (foo, bar, buz) {
    console.log(getFunctionParams(arguments.callee));
};
myPrivateFunction (1, 2);

// Solution 2.
var myFunction = function someFunc (foo, bar, buz) {
    // some code
};
var params = getFunctionParams(myFunction);
console.log(params);

// Solution 3.
var cls = function SuperKewlClass (foo, bar, buz) {
    // some code
};
var inst = new cls();
var params = getFunctionParams(inst.constructor);
console.log(params);

享受与JS!

UPD:实际上杰克·艾伦提供了一个更好的解决方案。GJ杰克!

我不知道如何得到参数列表但是你可以这样做来得到它期望的数量。注意，这只计算签名中没有默认值的参数:

函数foobar(a, b, c) {} 函数foobar2(a, b=false, c=false) {} console.log (foobar.length);//打印3个 console.log (foobar2.length);//打印1个

//See this:


// global var, naming bB
var bB = 5;

//  Dependency Injection cokntroller
var a = function(str, fn) {
  //stringify function body
  var fnStr = fn.toString();

  // Key: get form args to string
  var args = fnStr.match(/function\s*\((.*?)\)/);
  // 
  console.log(args);
  // if the form arg is 'bB', then exec it, otherwise, do nothing
  for (var i = 0; i < args.length; i++) {
    if(args[i] == 'bB') {
      fn(bB);
    }
  }
}
// will do nothing
a('sdfdfdfs,', function(some){
alert(some)
});
// will alert 5

a('sdfdsdsfdfsdfdsf,', function(bB){
alert(bB)
});

// see, this shows you how to get function args in string