js for,while 正序降序循环遍历数组

var arr = ["小强","小红","小明","小白"];

js for循环正序

for(var i = 0;i<arr.length;i++){

 console.log("My name is " + arr[i] + "!");

};

for(var i in arr){

 console.log("My name is " + arr[i] + "!");

}

js for循环降序

for(var i in arr.reverse()){

  console.log("My name is " + arr[i] + "!");

}

js while循环正序

var i = 0;

while(i<=2){

 console.log("My name is " + arr[i] + "!");

i++;

}

js while循环降序

var i = 2;

while(i >= 0){

 console.log("My
name is " + arr[i] + "!");

 i--;

}