• 打亂數(shù)組

var a=[1,2,3,4,5,6,7,8];
function change(arr){
    var NewArr = arr.sort(function(){Math.random()-0.5});//正負(fù)交替出現(xiàn)
    return NewArr;
}

• 返回結(jié)果ture是-1或者false是0

~"haha".indexOf("h");
>>-1
~"haha".indexOf("e");
>>0
~"hagha".indexOf("g");
>>-1

• 返回?cái)?shù)組中某一個(gè)值

var a=["a","b","c","d","e"];
console.log(a[~~(Math.random()*a.length)]);
//方法一，位運(yùn)算符~的實(shí)現(xiàn)
["a","b","c","d","e"][Math.floor(Math.random()*5)]
//方法二，Math.floor()方法

• js操作表單（單選框）

var timeForm = radiobox.getElementsByTagName('input');
for (var i = 0; i < timeForm.length; i++) {    
      if (timeForm[i].checked) {        
            pageState.nowGraTime = timeForm[i].value;  
      }
}//這樣OK

var timeForm = radiobox.getElementsByTagName('input');
for (var i = 0; i < timeForm.length; i++) {    
      if (timeForm[i].getAttribute(checked)) {        
            pageState.nowGraTime = timeForm[i].value;  
      }
}//這樣NO

原因：
getAttribute獲取checkbox或者radio的checked值在各個(gè)瀏覽器不同。
E6/7 ：依次返回 false/true
IE8 ：依次返回 空字符串/checked
IE9/10/Firefox/Safari/Chrome/Opera ：依次返回 null/空字符串

• 高逼格代碼(兩段代碼作用相同，換位判斷是否變號)

var swip = function (turnleft) { //0 是 false   
         var r = (turnleft ? !!direction[0] : !!direction[1]) ? -1 : 1;  
         direction[0] += direction[1];    
         direction[1] = direction[0] * r - direction[1] * r;      
         direction[0] = direction[0] * r - direction[1];    
         angle += turnleft ? -90 : 90;    
         block.style.transform = "rotate(" + angle + "deg)";
};

var swipa = function (turnleft) {    
         var r;    
         if (turnleft) {        
               r = ( !!direction[0] ) ? -1 : 1;   
         } else {       
              r = ( !!direction[1]) ? -1 : 1;    
         }   
         var c;    
         c = direction[0];   
         direction[0] = direction[1] * r;    
         direction[1] = c * r;    
         angle += turnleft ? -90 : 90;   
         block.style.transform = "rotate(" + angle + "deg)";
};