在nodejs中用setTimeout时 第一个参数用字符串 为什么会报错？

Question

直接贴代码for(var i=0;i<5;i++){    setTimeout('fn()',1000);}function fn(){console.log(i)}报错为TypeError: "callback" argument must be a function但是在chrome中用不会报错，可以运行。这是怎么回事？

Answer 1

nodejs环境下和浏览器环境下不同

在nodejs环境下

If callback is not a function, a TypeError will be thrown.

在浏览器环境下,也是不推荐使用的

An optional syntax allows you to include a string instead of a function, which is compiled and executed when the timer expires. This syntax is not recommended for the same reasons that make using eval() a security risk.