JavaScript确实是一种单线程语言，但支持异步代码。那是什么意思？这意味着没有两个代码块会同时运行。在像Java这样的多线程语言中，两个函数可以同时运行，每个函数都在自己的线程上运行。然而，在JavaScript中，即使使用异步代码，所有需要运行的代码都将被放入一个“队列”中，只是代码的顺序最终在“队列”中取决于您的逻辑是否是同步的。例如：const work = (a) => { console.log('Starting work: ' + a); // Here we simulate some long operation for (let i = 0; i < 100000; i++) { document.querySelector('a[href]'); } console.log('Finished work: ' + a);};work(1);work(2);work(3);setTimeout(() => work(4), 2);setTimeout(() => work(5), 1);work(6);work(7);您将在输出上看到的是：Starting work: 1Finished work: 1Starting work: 2Finished work: 2Starting work: 3Finished work: 3Starting work: 6Finished work: 6Starting work: 7Finished work: 7Starting work: 4 <- This one was asyncFinished work: 4 <- This one was asyncStarting work: 5 <- This one was asyncFinished work: 5 <- This one was async因此，即使有一些异步代码，函数总是启动和完成，而不会异步代码在执行中途“中断”它。work