JavaScript连载21-合并数组、数组中的sort函数实现原理

    //合并多个数组concat
    var arr = ["zhangsan","lisi","wangwu"];
    var arr1 = ["zhaoli","liqi"];
    var arr2 = ["xiaoliao"];
    var newArr = arr.concat(arr1);//合并了两个数组
    console.log(newArr)

    //indexOf()和lastIndexOf()
    var n1 = 3;
    var arr3 = [5,3,5,77,4,5,6,8];
    console.log(arr3.indexOf(5, 0));
    console.log(arr3.lastIndexOf(5, 5));

    //forEach遍历
    var arr4 = ["zhangsan","lisi","wangwu"];
    arr4.forEach(function (value,index,array) {
        console.log(value);
        console.log(index);
        console.log(array);
    })

   //sort函数
    var arr5 = ["Tim","Andy","John","Kobe","James"];
    console.log(arr5.sort());
    var arr6 = [10,4,8,6,7,100];
    console.log(arr6.sort());//可以看出即使是数字也会按照编码规则进行排序，而不是按照数字大小来进行排序
    function sortNumber(a,b) {
        return a-b;//
    }
    console.log(arr6.sort(sortNumber));//把这个比较函数传入就可以改写sort的排序逻辑

    /**
     * sort的内部实现
     * @param {Array}array
     * @param {Function}fnCompare
     */
    function sort(array,fnCompare){
        //这个排序方法是冒泡排序，并且是先排大的值。
        for(var i=0;i<array.length-1;i++){//可以看出数组的长度函数和Java一样
            //标记是否完成了排序
            var sortFlag = true;
            //控制比较次数
            for(var j=0;j<array.length-1-i;j++){
                if(fnCompare(array[j],array[j+1])>0){//如果没有>0的话，那就会出现永真的状况
                    sortFlag = false;
                    //交换位置
                    var temp = array[j];
                    array[j] = array[j+1];
                    array[j+1] = temp;
                }
            }
            //判断
            if (sortFlag){
                break;
            }
        }
    }
    var arr7 = [10,20,5,1000,50];
    sort(arr7,sortNumber);
    console.log(arr7);