Iterators and promises replace async/await

function awaitDome(){
	return new Promise((r) = > {
	setTimeout(function(){
		r(1)
		console.log(1)},2000)})}async function asyncDome(){
	console.log('await'.await awaitDome())
	console.log(2)}Copy the code

This is easy if there is only one asynchronous operation

function awaitDome(){
	return new Promise((r) = > {
	setTimeout(function(){
		r(1)
		console.log(1)},2000)
	}) 
}
awaitDome().then(r= > console.log(r))
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If it’s a loop or multiple, if you’re dealing with a list of arrays in order now and you’re not doing it synchronously, you might not want to do it if you’re not doing it synchronously. For example, if you’re doing a waterfall of your applet, you need to add elements one by one to get the height of the list

/ / the iterator
var a = [1.2.3.4.5.6.7]
function createIterator(items) {
    var i = 0;
    return {
        next: function() {
            var done = (i >= items.length);
            varvalue = ! done ? items[i++] :undefined;
            return {
                done: done,
                value: value }; }}; }var iteratorDome = createIterator(a)
function awaitDome(i){
	return new Promise((r) = > {
		setTimeout(function(){
			r(i)
		},2000)})}function next(){
	var iterator = iteratorDome.next()
	console.log(iterator)
	awaitDome(iterator.value).then(r= > {
		console.log(r)
		if(! iterator.done){ next() } }) } next()// Execute the following result
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If you just loop through it

var gg = new Date(a)var a = [1.2.3.4.5.6.7]
function awaitDome(i){
	return new Promise((r) = > {
		
		setTimeout(function(){
			r(i)
			console.log(new Date() - gg)
		},i * 500)
	}) 
}

a.forEach((e) = > {
	awaitDome(e).then(r= > {
		console.log(r)
	})
})

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The figure above shows the basic 500ms execution but actually wants the result

/ / the iterator
var gg = new Date(a)var a = [1.2.3.4.5.6.7]
function createIterator(items) {
    var i = 0;
    return {
        next: function() {
            var done = (i >= items.length);
            varvalue = ! done ? items[i++] :undefined;
            return {
                done: done,
                value: value }; }}; }var iteratorDome = createIterator(a)
function awaitDome(i){
	return new Promise((r) = > {
			
		setTimeout(function(){
			r(i)
			console.log(new Date() - gg)
		},i * 500)})}function next(){
	var iterator = iteratorDome.next()
	console.log(iterator)
	awaitDome(iterator.value).then(r= > {
		console.log(r)
		if(! iterator.done){ next() } }) } next()// Execute the following result
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Because normally we call the interface and the order in which the data is returned is asynchronous and when we want to return in order we have to synchronizeIn accordance with theCalled sequentially