es6/underscore

[qw789]

.each(array, iteratee) ES5.1 array.forEach(iteratee) .map(array, iteratee) ES5.1 array.map(iteratee) .reduce(array, iteratee, memo) array.reduce(iteratee, memo) .reduceRight(array, iteratee, memo) array.reduceRight(iteratee, memo) .every(array, predicate) array.every(predicate) .some(array, predicate) array.some(predicate) .find(array, predicate) array.find(predicate) .pluck(array, propertyName) ES2015 array.map(value => value[propertyName]) _.includes(array, element) ES2016 array.includes(element)

[qw789]

类的方法中有this时最好带一个bind。否则把这个方法单独使用时实例会是运行环境。

[qw789]

二、setTimeout(this.method, time)这种形式中的this，即上文中提到的第一个this，是根据上下文来判断的，默认为全局作用域，但不一定总是处于全局下，具体问题具体分析。

[qw789]

const promise = new Promise((resolve, reject) => { resolve('success1') reject('error') resolve('success2') })

promise .then((res) => { console.log('then: ', res) }) .catch((err) => { console.log('catch: ', err) })

then: success1

[qw789]

const getRandom = () => +(Math.random()*1000).toFixed(0);

const asyncTask = taskID => new Promise(resolve => { let timeout = getRandom(); console.log(taskID=${taskID} start.); setTimeout(function() { console.log(taskID=${taskID} finished in time=${timeout}.); resolve(taskID) }, timeout); });

Promise.all([asyncTask(1),asyncTask(2),asyncTask(3)]) .then(resultList => { console.log('results:',resultList); });

[qw789]

taskID=1 start. VM20439:5 taskID=2 start. VM20439:5 taskID=3 start. Promise {} VM20439:7 taskID=3 finished in time=102. VM20439:7 taskID=2 finished in time=426. VM20439:7 taskID=1 finished in time=783. VM20439:14 results: (3) [1, 2, 3]

[qw789]

var a = new Promise(function (resolve,reject) { console.log(1); setTimeout(function () { console.log(11); resolve('aaa'); },1000); });

var b = new Promise(function (resolve,reject) { console.log(2); setTimeout(function () { console.log(22);
resolve('bbb'); },300); });

var p = Promise.all([a,b]); p.then(function(val) { console.log(val); });

}); // 1 // 2 // 22 // 11 // ["aaa", "bbb"]

[qw789]

如何在 Web 关闭页面时发送 Ajax 请求 navigator.sendBeacon