是否有一种方法可以动态地获取函数的函数参数名?

假设我的函数是这样的

function doSomething(param1, param2, .... paramN){
   // fill an array with the parameter name and value
   // some other code 
}

现在,我如何从函数内部获得参数名称及其值的列表到数组中?


当前回答

//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

其他回答

这个包使用重铸来创建AST,然后从它们收集参数名,这允许它支持模式匹配,默认参数,箭头函数和其他ES6特性。

https://www.npmjs.com/package/es-arguments

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]);    

好了,这是个老问题,有很多足够的答案。 下面是我提供的不使用正则表达式的产品,除了去除空白的琐碎任务。(我应该注意到,“strips_comments”函数实际上是将它们分隔开来,而不是从物理上删除它们。这是因为我在其他地方使用它,由于各种原因需要原始非注释令牌的位置保持完整)

这是一个相当长的代码块,因为这个粘贴包含一个迷你测试框架。

    function do_tests(func) {

    if (typeof func !== 'function') return true;
    switch (typeof func.tests) {
        case 'undefined' : return true;
        case 'object'    : 
            for (var k in func.tests) {

                var test = func.tests[k];
                if (typeof test==='function') {
                    var result = test(func);
                    if (result===false) {
                        console.log(test.name,'for',func.name,'failed');
                        return false;
                    }
                }

            }
            return true;
        case 'function'  : 
            return func.tests(func);
    }
    return true;
} 
function strip_comments(src) {

    var spaces=(s)=>{
        switch (s) {
            case 0 : return '';
            case 1 : return ' ';
            case 2 : return '  ';
        default : 
            return Array(s+1).join(' ');
        }
    };

    var c1 = src.indexOf ('/*'),
        c2 = src.indexOf ('//'),
        eol;

    var out = "";

    var killc2 = () => {
                out += src.substr(0,c2);
                eol =  src.indexOf('\n',c2);
                if (eol>=0) {
                    src = spaces(eol-c2)+'\n'+src.substr(eol+1);
                } else {
                    src = spaces(src.length-c2);
                    return true;
                }

             return false;
         };

    while ((c1>=0) || (c2>=0)) {
         if (c1>=0) {
             // c1 is a hit
             if ( (c1<c2) || (c2<0) )  {
                 // and it beats c2
                 out += src.substr(0,c1);
                 eol = src.indexOf('*/',c1+2);
                 if (eol>=0) {
                      src = spaces((eol-c1)+2)+src.substr(eol+2);
                 } else {
                      src = spaces(src.length-c1);
                      break;
                 }
             } else {

                 if (c2 >=0) {
                     // c2 is a hit and it beats c1
                     if (killc2()) break;
                 }
             }
         } else {
             if (c2>=0) {
                // c2 is a hit, c1 is a miss.
                if (killc2()) break;  
             } else {
                 // both c1 & c2 are a miss
                 break;
             }
         }

         c1 = src.indexOf ('/*');
         c2 = src.indexOf ('//');   
        }

    return out + src;
}

function function_args(fn) {
    var src = strip_comments(fn.toString());
    var names=src.split(')')[0].replace(/\s/g,'').split('(')[1].split(',');
    return names;
}

function_args.tests = [

     function test1 () {

            function/*al programmers will sometimes*/strip_comments_tester/* because some comments are annoying*/(
            /*see this---(((*/ src//)) it's an annoying comment does not help anyone understand if the 
            ,code,//really does
            /**/sucks ,much /*?*/)/*who would put "comment\" about a function like (this) { comment } here?*/{

            }


        var data = function_args(strip_comments_tester);

        return ( (data.length==4) &&
                 (data[0]=='src') &&
                 (data[1]=='code') &&
                 (data[2]=='sucks') &&
                 (data[3]=='much')  );

    }

];
do_tests(function_args);

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。

//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