版权声明:谁没个菜的时候! https://blog.csdn.net/qq_32584661/article/details/81536341
没隔3s输出一个数字,即,3s输出1,3s后再输出2...
for (var i = 1; i < 4; i++) {
(function(a) {
setTimeout(function() {
console.log(a);
}, a*3000); //.....
})(i)
}