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
正确的方法是使用JS解析器。下面是一个使用橡子的例子。
const acorn = require('acorn');
function f(a, b, c) {
// ...
}
const argNames = acorn.parse(f).body[0].params.map(x => x.name);
console.log(argNames); // Output: [ 'a', 'b', 'c' ]
这里的代码查找函数f的三个(形式)参数的名称。它通过将f输入acorn.parse()来实现。
其他回答
这是我的解决方案——它适用于命名函数和未命名函数，异步和非异步函数，异步和非异步lambdas，以及带和不带paren的lambdas。
const STRIP_COMMENTS = /((\/\/.*$)|(\/\*.*\*\/))/mg;
const STRIP_KEYWORDS = /(\s*async\s*|\s*function\s*)+/;
const ARGUMENT_NAMES = /\(([^)]+)\)\s*=>|([a-zA-Z_$]+)\s*=>|[a-zA-Z_$]+\(([^)]+)\)|\(([^)]+)\)/;
const ARGUMENT_SPLIT = /[ ,\n\r\t]+/;
function getParamNames(func) {
const fnStr = func.toString()
.replace(STRIP_COMMENTS, "")
.replace(STRIP_KEYWORDS, "")
.trim();
const matches = ARGUMENT_NAMES.exec(fnStr);
var match;
if (matches) {
for (var i = 1; i < matches.length; i++) {
if (matches[i]) {
match = matches[i];
break;
}
}
}
if (match === undefined) {
return [];
}
return match.split(ARGUMENT_SPLIT).filter(part => part !== "");
}
我以前试过这样做，但从来没有找到一个实用的方法来完成它。我最终传递了一个对象，然后循环遍历它。
//define like
function test(args) {
for(var item in args) {
alert(item);
alert(args[item]);
}
}
//then used like
test({
name:"Joe",
age:40,
admin:bool
});
注意:如果你想使用ES6参数解构与顶部解决方案添加下面的行。
if (result[0] === '{' && result[result.length - 1 === '}']) result = result.slice(1, -1)
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]);
这个问题的答案需要3个步骤:
To get the values of the actual parameters passed to the function (let's call it argValues). This is straight forward as it will be available as arguments inside the function. To get the parameter names from the function signature (let's call it argNames). This not as easy and requires parsing the function. Instead of doing the complex regex yourself and worrying about edge cases (default parameters, comments, ...), you can use a library like babylon that will parse the function into an abstract syntax tree from which you can obtain the names of parameters. The last step is to join the 2 arrays together into 1 array that has the name and value of all the parameters.
代码是这样的
const babylon = require("babylon")
function doSomething(a, b, c) {
// get the values of passed argumenst
const argValues = arguments
// get the names of the arguments by parsing the function
const ast = babylon.parse(doSomething.toString())
const argNames = ast.program.body[0].params.map(node => node.name)
// join the 2 arrays, by looping over the longest of 2 arrays
const maxLen = Math.max(argNames.length, argValues.length)
const args = []
for (i = 0; i < maxLen; i++) {
args.push({name: argNames[i], value: argValues[i]})
}
console.log(args)
// implement the actual function here
}
doSomething(1, 2, 3, 4)
日志对象将为
[
{
"name": "a",
"value": 1
},
{
"name": "c",
"value": 3
},
{
"value": 4
}
]
下面是一个工作示例https://tonicdev.com/5763eb77a945f41300f62a79/5763eb77a945f41300f62a7a
