javascript 里的循环

for

for(var i = 0; i< 10; i++) { console.log(i) }

for in

for in 语句用于循环对象属性。 循环中的代码每执行一次，就会对数组的元素或者对象的属性进行一次操作。

var a=[3,4,5,7]; for(var test in a){ document.write(test ": " a[test] ""); } var person = {fname:"John", lname:"Doe", age:25}; var text = ""; var x; for (x in person) { text += person[x]; } // text // John Doe 25

do while

var i = 0 do { document.write( i "") i }while (i <= 5) // i 等于 0。 循环首先会运行。 每循环一次，i 就会累加 1。 当 i 小于或等于 5 时，循环会继续运行。

while

var j = 0 while ( j<= 5) { document.write("数字是 " j) document.write("")j } // j 等于 0。 当 j 小于或等于 5 时，循环将继续运行。 循环每运行一次，j 会累加 1。

switch

var day=new Date().getDay(); switch (day){ case 0: x="Today it's Sunday"; break; case 1: x="Today it's Monday"; break; case 2: x="Today it's Tuesday"; break; case 3: x="Today it's Wednesday"; break; case 4: x="Today it's Thursday"; break; case 5: x="Today it's Friday"; break; case 6: x="Today it's Saturday"; break; } document.write( x)