【JS】JavaScript Promise

代码举例

	function test(resolve, reject) {
		let timeOut = Math.random() * 2;
		console.log("11")
		
		setTimeout(function() {
			if(timeOut < 1) {
				console.log("ok", timeOut)
				resolve("ok " + timeOut);
			}else {
				console.log("timeOut", timeOut)
				reject("error " + timeOut);
			}
		}, timeOut * 1000);
		console.log("22")
	}
	
	console.log("1");
	
	//方式1
	new Promise(test).then(result => {
		console.log("ok", result);
	}).catch(result => {
		console.log("error", result);
	})
	
	console.log("2");

方式1

	new Promise(test).then(result => {
		console.log("ok", result);
	}).catch(result => {
		console.log("error", result);
	})

方式2

	new Promise(test).then(
		(result) => {
			console.log("ok", result);
		},
		(error) => {
			console.log("error", error);
		}
	)

执行结果

注意

then, catch, finally 顺序不能颠倒。