这里很多答案都使用正则表达式，这很好，但是它不能很好地处理语言的新添加内容（例如箭头函数和类）。还要注意的是，如果您在缩小的代码上使用这些功能中的任何一个，它将to。它将使用最小的名称。Angular通过允许您在DI容器中注册参数时传递一个与参数顺序匹配的有序字符串数组来解决此问题。以此类推：
var esprima = require('esprima');
var _ = require('lodash');
const parseFunctionArguments = (func) => {
// allows us to access properties that may or may not exist without throwing
// TypeError: Cannot set property 'x' of undefined
const maybe = (x) => (x || {});
// handle conversion to string and then to JSON AST
const functionAsString = func.toString();
const tree = esprima.parse(functionAsString);
console.log(JSON.stringify(tree, null, 4))
// We need to figure out where the main params are. Stupid arrow functions 👊
const isArrowExpression = (maybe(_.first(tree.body)).type == 'ExpressionStatement');
const params = isArrowExpression ? maybe(maybe(_.first(tree.body)).expression).params
: maybe(_.first(tree.body)).params;
// extract out the param names from the JSON AST
return _.map(params, 'name');
};
这可以处理原始的解析问题以及其他一些函数类型（例如，箭头函数）。这是它可以处理和不能处理的想法：
// I usually use mocha as the test runner and chai as the assertion library
describe('Extracts argument names from function signature. 💪', () => {
const test = (func) => {
const expectation = ['it', 'parses', 'me'];
const result = parseFunctionArguments(toBeParsed);
result.should.equal(expectation);
}
it('Parses a function declaration.', () => {
function toBeParsed(it, parses, me){};
test(toBeParsed);
});
it('Parses a functional expression.', () => {
const toBeParsed = function(it, parses, me){};
test(toBeParsed);
});
it('Parses an arrow function', () => {
const toBeParsed = (it, parses, me) => {};
test(toBeParsed);
});
// ================= cases not currently handled ========================
// It blows up on this type of messing. TBH if you do this it deserves to
// fail 😋 On a tech note the params are pulled down in the function similar
// to how destructuring is handled by the ast.
it('Parses complex default params', () => {
function toBeParsed(it=4*(5/3), parses, me) {}
test(toBeParsed);
});
// This passes back ['_ref'] as the params of the function. The _ref is a
// pointer to an VariableDeclarator where the ✨🦄 happens.
it('Parses object destructuring param definitions.' () => {
function toBeParsed ({it, parses, me}){}
test(toBeParsed);
});
it('Parses object destructuring param definitions.' () => {
function toBeParsed ([it, parses, me]){}
test(toBeParsed);
});
// Classes while similar from an end result point of view to function
// declarations are handled completely differently in the JS AST.
it('Parses a class constructor when passed through', () => {
class ToBeParsed {
constructor(it, parses, me) {}
}
test(ToBeParsed);
});
});
根据您想将其用于ES6代理的不同，进行销毁可能是最好的选择。例如，如果您想将其用于依赖项注入（使用参数的名称），则可以按以下方式进行操作：
class GuiceJs {
constructor() {
this.modules = {}
}
resolve(name) {
return this.getInjector()(this.modules[name]);
}
addModule(name, module) {
this.modules[name] = module;
}
getInjector() {
var container = this;
return (klass) => {
console.log(klass);
var paramParser = new Proxy({}, {
// The `get` handler is invoked whenever a get-call for
// `injector.*` is made. We make a call to an external service
// to actually hand back in the configured service. The proxy
// allows us to bypass parsing the function params using
// taditional regex or even the newer parser.
get: (target, name) => container.resolve(name),
// You shouldn't be able to set values on the injector.
set: (target, name, value) => {
throw new Error(`Don't try to set ${name}! 😑`);
}
})
return new klass(paramParser);
}
}
}
它不是目前最先进的解析器，但是它为您提供了一个思路，如果您想使用args解析器进行简单的DI，则可以使用代理来处理它。但是，此方法有一点警告。我们需要使用解构分配而不是常规参数。当我们传递注入器代理时，解构与在对象上调用getter相同。
class App {
constructor({tweeter, timeline}) {
this.tweeter = tweeter;
this.timeline = timeline;
}
}
class HttpClient {}
class TwitterApi {
constructor({client}) {
this.client = client;
}
}
class Timeline {
constructor({api}) {
this.api = api;
}
}
class Tweeter {
constructor({api}) {
this.api = api;
}
}
// Ok so now for the business end of the injector!
const di = new GuiceJs();
di.addModule('client', HttpClient);
di.addModule('api', TwitterApi);
di.addModule('tweeter', Tweeter);
di.addModule('timeline', Timeline);
di.addModule('app', App);
var app = di.resolve('app');
console.log(JSON.stringify(app, null, 4));
输出以下内容：
{
"tweeter": {
"api": {
"client": {}
}
},
"timeline": {
"api": {
"client": {}
}
}
}
它连接了整个应用程序。最好的一点是，该应用程序易于测试（您可以实例化每个类并传递模拟/存根/等）。同样，如果您需要换出实现，则可以在一个地方进行。由于JS Proxy对象，所有这些都是可能的。
注意：在准备投入生产使用之前，需要做很多工作，但是确实可以使您了解它的外观。
答案有点晚了，但可能会帮助想到同一件事的其他人。👍
