javascript 循环 while ，for ，switch ，do..while，for ..in/for..of 区别
循环实例：<!--do...while循环--><script>do { var input = prompt('How are you')} while (!input);</script>for循环获取所有的偶数:<script>for (var num = 0; num <= 12; num += 2) {doc...
