理解 Co 库的源码

Co 流程流程控制器源码与理解,index.js 包含理解和注释

简单版本的 Co 库

这个版本是重点是理解 generator 工作原理

// @flow /** * Created by Freax on 16-12-12. * @Blog http://www.myfreax.com/ */ function co(generator) { let gen = generator(); next(gen.next()); //递归遍历 generator.next function next(result) { if (result.done)return null;//如果 generator 执行完毕，直接解决退出遍历 let res = gen.next(result.value); next(res); } } co(function *gen() { let a = yield 1; console.info(a, 'a'); let b = yield 2; console.info(b, 'b'); let c = yield 3; console.info(c, 'c'); }); 

generator+promise Co 库的简版

理解 generator+promise 如何工作

// @flow /** * Created by Freax on 16-12-12. * @Blog http://www.myfreax.com/ */ function isPromise(obj) { return typeof obj === 'object' && 'function' == typeof obj.then; } function co(generator) { return new Promise((resolve,reject)=>{ let gen = generator(); next(gen.next()); function next(result) { if (result.done)return resolve(result.value);//如果 generator 执行完毕，直接解决退出遍历 //判断是否是 Promise ，如果是 promise 则执行 promise 再进入 next 递归遍历 generator.next if (isPromise(result.value))return result.value.then(res => { let result; try { result = gen.next(res); //抛出 generator 的错误 }catch (e){ return reject(e);// 捕获后由交给 promise 处理返回外部处理 } next(result) }, err => { let result; try { result = gen.throw(err); //yield 返回 promise 进入 reject 后的错误，抛出 generator 的错误 }catch (e){ return reject(e); // 捕获后由交给 promise 处理返回外部处理 } next(result) }); let res = gen.next(result.value); next(res); } }); } co(function *gen() { let a = yield Promise.resolve(1); console.info(a, 'a'); let b = yield 2; console.info(b, 'b'); let c = yield 3; console.info(c, 'c'); }).catch((err)=>{ console.info(err); }); 

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