~：按位非操作符由一個(gè)波浪線（~）表示，執(zhí)行按位非的結(jié)果就是返回?cái)?shù)值的反碼。

復(fù)制代碼 代碼如下:

var num1 = 3;    // 我的幸運(yùn)數(shù)字是3
var num2 = ~(num1);
console.log(num2)  //  "-4"
var num3 = -3; 
var num4 = ~(num3);
console.log(num4)  //  "2"
console.log(~(0))  //  "-1"

復(fù)制代碼 代碼如下:

if (~item[search_key].toLowerCase().indexOf(query)) {
                        _results.push(item);
 }

復(fù)制代碼 代碼如下:

if( str.indexOf(query) != -1 )  or  if( str.indexOf(query) >= 0)

復(fù)制代碼 代碼如下:

var str = "hutaoer go go go!!!!! My lucky number is 33!!";
    var query = 33;
    var timeStart1 = new Date() - 0;
    for(var i = 0; i < 100000000; i++) {
        ~str.indexOf(query)
    }
    var timeEnd1 = new Date() - 0;
    console.log('~ cost time:' + (timeEnd1 - timeStart1));
    // ~ cost time:9954  循環(huán)次數(shù)：10000000
    // ~ cost time:104  循環(huán)次數(shù)： 100000
    var timeStart2 = new Date() - 0;
    for(var j = 0; j < 100000000; j++) {
        str.indexOf(query) >= 0
    }
    var timeEnd2 = new Date() - 0;
    console.log('>= cost time:' + (timeEnd2 - timeStart2));
   // >= cost time:10120  循環(huán)次數(shù)：10000000

復(fù)制代碼 代碼如下:

    var str = "hutaoer go go go!!!!! My lucky number is 33!!";
    var query = 33;
    var timeStart1 = new Date() - 0;
    for(var i = 0; i < 1000000; i++) {
        ~str.indexOf(query)
    }
    var timeEnd1 = new Date() - 0;
    console.log('~ cost time:' + (timeEnd1 - timeStart1));
    //  循環(huán)1000000次  127ms
    var timeStart2 = new Date() - 0;
    for(var j = 0; j < 1000000; j++) {
        str.indexOf(query) >= 0
    }
    var timeEnd2 = new Date() - 0;
    console.log('>= cost time:' + (timeEnd2 - timeStart2));
    // 循環(huán)1000000次 101ms
    var timeStart3 = new Date() - 0;
    for(var k = 0; k < 1000000; k++) {
        Boolean(~str.indexOf(query))
    }
    var timeEnd3 = new Date() - 0;
    console.log('add Boolean cost time:' + (timeEnd3 - timeStart3));
    // 循環(huán)1000000次 129ms
    var timeStart4 = new Date() - 0;
    for(var k = 0; k < 1000000; k++) {
        !!(~str.indexOf(query))
    }
    var timeEnd4 = new Date() - 0;
    console.log('add !! cost time:' + (timeEnd4 - timeStart4));
    // 循環(huán)10000000次 103ms