手写生成器

• 先done再false，不然index就提前了一步+1

var arr = [1,2]
function generator(arr){var i = 0;return{next(){var done = i > arr.length ? true : false,value = done ? 'undefined' : arr[i++];return {value : value,done : done}  }}
}
var gen = generator(arr);
console.log(gen.next());
console.log(gen.next());
console.log(gen.next());

应用一

• n个函数，点一次执行一个

顺序执行

• 用return false来中断执行

var fn = [function test1(){console.log(1);return true},function test2(){console.log(2);return false},function test3(){console.log(3);return true}
]
for(var i of fn){if(!i()){break}
}

中间件

• node express 洋葱模型
• 表单校验？获取验证码+登录+请求？获取token+校验token+打开页面？
• 递归 + 函数用next()控制下一次执行
• 用done控制传入数组内方法的执行
• 在每个方法里按具体业务控制next的执行

;(function(functions){function * doFun(arr){for(var i = 0; i < arr.length; i++){yield arr[i];}}var iterator = doFun(functions);var init=()=>{nextDo(iterator.next())}function nextDo(fn){fn.value(function(){var fn = iterator.next();if(!fn.done){nextDo(fn)}else{return}})}init()})
([function test1(next){console.log(1);next()  },function test2(next){console.log(2);next()  },function test3(next){console.log(3);next()  }]
)

模块化

// middleware.js
export const M = function(functions){function * doFun(arr){for(var i = 0; i < arr.length; i++){yield arr[i];}}var iterator = doFun(functions);var init=()=>{nextDo(iterator.next())}function nextDo(fn){fn.value(function(){var fn = iterator.next();if(!fn.done){nextDo(fn)}else{return}})}init()}
M([function test1(next){console.log(1);next()  },function test2(next){console.log(2);// 伪代码// if(token){//	next()// }next()  },function test3(next){console.log(3);next()  }]
)

打印日志

• TJ co/test/generator

var assert = require('assert');
var co = require('..');function sleep(ms) {return function(done){setTimeout(done, ms);}
}function *work() {yield sleep(50);return 'yay';
}describe('co(*)', function(){describe('with a generator function', function(){it('should wrap with co()', function(){return co(function *(){var a = yield work;var b = yield work;var c = yield work;assert('yay' == a);assert('yay' == b);assert('yay' == c);var res = yield [work, work, work];assert.deepEqual(['yay', 'yay', 'yay'], res);});})it('should catch errors', function(){return co(function *(){yield function *(){throw new Error('boom');};}).then(function () {throw new Error('wtf')}, function (err) {assert(err);assert(err.message == 'boom');});})})
})