• 常见算法


    js-查找字符串中出现次数最多的字符

    var str = "abcdffffggj";
    var obj = {};
    for(var i = 0; i < str.length; i++){
      //charAt() 方法可返回指定位置的字符。
    if(!obj[str.charAt(i)]){ obj[str.charAt(i)] = 1; }else{ obj[str.charAt(i)]++; } } console.log(obj); var max = 0, name = ""; for(var i in obj){ if(obj[i] > max){ max = obj[i]; name = i; } } console.log(name+":"+max);

    js找出两个数组中不同的元素

    var arr1 = [1,2,3];
    var arr2 = [2,3,4,5,6];
    
    let output = arr1
    .filter(x => arr2.indexOf(x) == -1)
    .concat(arr2.filter(x => arr1.indexOf(x) == -1));
    
    console.log(output);

    随机生成100个0~100之间的随机数

    var arr = [];
    for(var i = 0; i < 100; i++){
       arr[i]  = Math.floor(Math.random()*101);
    }
    console.log(arr);

    排序(冒泡排序)

    var sorted = true;
    for(var i = 0; i < arr.length; i++){ for(var j = 0; j < arr.length - 1 - i; j++){ if(arr[j] > arr[j+1]) { arr[j] = [arr[j+1],arr[j+1] = arr[j]][0]; sorted=false; } } if(sorted==true){ break; }
    }

    查找

    function search(arr,data){
            var max = arr.length-1,  //最大值
                min = 0;  //最小值
            while(min<=max){
                var mid = Math.floor((max+min)/2); //中间值
                if(arr[mid]<data){
                    min = mid+1;
                }else if(arr[mid]>data){
                    max = mid-1;
                }else{
                    return mid; 
                }
            }
            return -1;   //没找到返回-1
        }
        console.log(arr);//[0, 1, 2, 2, 3, 4, 4, 4, 5, 6, 7, 10, 11, 12, 14, 15, 16, 17, 18, 18, 20, 21, 23, 24, 24, 24, 25, 25, 25, 26, 28, 28, 34, 35, 35, 38, 39, 39, 40, 40, 42, 44, 48, 48, 49, 51, 51, 51, 53, 54, 54, 54, 55, 56, 58, 59, 59, 59, 60, 61, 62, 62, 63, 63, 65, 66, 67, 68, 68, 69, 69, 71, 71, 72, 73, 74, 76, 76, 77, 82, 83, 84, 85, 86, 86, 86, 86, 87, 90, 91, 91, 94, 94, 94, 94, 95, 95, 97, 98, 100]
      console.log(search(arr,25)); //27
        console.log(search(arr,104)); //-1

    查找重复次数(通过向左向右遍历查找重复出现的次数。)

    function count(arr,data){
            var count = 0;
            var position = search(arr,data);
            if(position>-1){
                count++;
                for(var i=position-1;i>0;i--){
                    if(arr[i]==data){
                        count++;
                    }else{
                        break;
                    }
                }
                for(var i=position+1;i<arr.length;i++){
                    if(arr[i]==data){
                        count++;
                    }else{
                        break;
                    }
                }
            }
            return count;
        }
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  • 原文地址:https://www.cnblogs.com/JQstronger/p/charAt.html
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