js系列四十五:异常处理

在Promise中,是通过catch的方式来捕获异常,而当使用async时,则通过try/catch来捕获异常.

function fn() {
	return new Promise((resolve, reject)=>{
		setTimeout(() => {
			reject("some error");
		}, 1000);
	})
}
const fn = async ()=>{
	try {
		await fn();
	}catch(e) {
		console.log(e);
	}
}
foo();

如果有多个await函数,那么只返回第一个捕获异常

function fn() {
	return new Promise((resolve,reject)=>{
		setTimeout(()=>{
			reject("some error");
		}, 1000);
	})
}

function fn2() {
	return new Promise((resolve, reject)=>{
		setTimeout(()=>{
			reject("some error fn2");
		},1000);
	})
}

const foo = async () => {
	try {
		await fn1();
		await fn2();
	}catch(e){
		console.log(e)
	}
}
foo();

在实践中遇到异步场景最多的就是接口的请求,因此这里就以Jquery中$.get为例,简单展示一下.

const clickUserInfo = () => $.get("xxxx/api/xx");
const clickHandler = async() => {
	try {
		const res = await getUserInfo();
		console.log(res);
	}catch(e) {
		//
	}
}