摘要：排序，數(shù)組去重，打亂數(shù)組，統(tǒng)計數(shù)組各個元素出現(xiàn)的次數(shù)，字符串各個字符的出現(xiàn)次數(shù)，獲取地址鏈接的各個參數(shù)以后會記錄自己解決過和遇到過的算法相關(guān)的題，系列一就以常見的開篇吧。

以后會記錄自己解決過和遇到過的算法相關(guān)的題，系列一就以常見的開篇吧。

本來想多列幾個排序方法，但是其它都不常見，更多請點擊查看，冒泡排序和快速排序中以快速排序最優(yōu)。

var arr = [0, 4, 2, 1, 3];
var i = j = 0;
for(i; i" 從小到大排序
        // "<" 從大到小排序
        if(arr[j] > arr[j+1]){
            temp = arr[j]
            arr[j] = arr[j+1]
            arr[j+1] = temp
        }
    }
}

console.log(arr);

function quickSort(arr){
    //如果數(shù)組<=1,則直接返回
    if (arr.length <= 1) { return arr; }
    var pivotIndex = Math.floor(arr.length/2);
    //找基準(zhǔn)，并把基準(zhǔn)從原數(shù)組刪除
    var pivot = arr.splice(pivotIndex,1)[0];
    //定義左右數(shù)組
    var left = [];
    var right = [];

    //比基準(zhǔn)小的放在left，比基準(zhǔn)大的放在right
    for (var i=0;i
數(shù)組去重
1. 遍歷數(shù)組法
var arr = ["2", 1, 5, 4, 7, "9", 4, 1, "2", 6, 8, 2];
for (var i = 0, newArr = [], len = arr.length; i < len; i++){
    if (newArr.indexOf(arr[i]) == -1) {
        newArr.push(arr[i]);
    }
}
console.log(newArr);
2. 數(shù)組下標(biāo)判斷法
var arr = ["2", 1, 5, 4, 7, "9", 4, 1, "2", 6, 8, 2];
for (var i = 1, newArr = [arr[0]], len = arr.length; i < len; i++){
    if (arr.indexOf(arr[i]) == i) {
        newArr.push(arr[i]);
    }
}
console.log(newArr);
3. 對象鍵值對法
var arr = ["2", 1, 5, 4, 7, "9", 4, 1, "2", 6, 8, 2];
for (var i = 0, obj = {}, newArr = [], len = arr.length, val, type; i < len; i++){
    val = arr[i];
    type = typeof val;
    if (!obj[val]) {  // 對象沒有該鍵對應(yīng)的值
        obj[val] = type;
        newArr.push(val);
    } else if (obj[val].indexOf(type) < 0) {//對象有該鍵對應(yīng)的值且它的值是不重復(fù)的
        obj[val] = type;
        newArr.push(val);
    }
}
console.log(newArr);
4. 排序后相鄰去除法
var arr = ["2", 1, 5, 4, 7, "9", 4, 1, "2", 6, 8, 2];
arr.sort();
var newArr = [arr[0]];
for (var i = 1, len = arr.length; i < len; i++) {
    if (arr[i] !== newArr[newArr.length-1]) {
        newArr.push(arr[i]);
    }
}
console.log(newArr);
5. 優(yōu)化遍歷數(shù)組法
var arr = ["2", 1, 5, 4, 7, "9", 4, 1, "2", 6, 8, 2];
for (var i = 0, len = arr.length, newArr = []; i < len; i++) {
    for (var j = i + 1; j < len; j++) {
        if (arr[i] === arr[j]) j = ++i;
    }
    newArr.push(arr[i]);
}
console.log(newArr);
6. 利用splice直接在原數(shù)組進(jìn)行操作
var arr = ["2", 1, 5, 4, 7, "9", 4, 1, "2", 6, 8, 2];
for (var i = 0, len = arr.length; i < len; i++) {
    for (var j = i + 1; j < len; j++) {
        if (arr[i] === arr[j]) {
            arr.splice(j, 1);
            len--;
            j--;
        }
    }
}
console.log(arr);
7. es6簡化版
var arr = ["2", 1, 5, 4, 7, "9", 4, 1, "2", 6, 8, 2];
// 7.1
var newArr = [...new Set(arr)]; 
console.log(newArr);

// 7.2
var newArr = Array.from(new Set(arr));
console.log(newArr);
// 數(shù)組去重，打亂數(shù)組，統(tǒng)計數(shù)組各個元素出現(xiàn)的次數(shù)， 字符串各個字符的出現(xiàn)次數(shù)，獲取地址鏈接的各個參數(shù)

打亂數(shù)組
var arr = [2,5,"6",3,9,"2",4,7];
arr.sort(function(){ return 0.5 - Math.random() });
console.log(arr);
統(tǒng)計數(shù)組各個元素出現(xiàn)的次數(shù)
1. 自創(chuàng)
var arr = ["2", 1, 5, 4, 7, "9", 4, 1, "2", 6, 8, 2];
for (var i = 0, len = arr.length, newArr = []; i < len; i++) {
    var isPush = true;
    for (var j = 0, l = newArr.length; j < l; j++) {
        if (arr[i] === newArr[j].val) {
            isPush = false;
            newArr[j].count++;
        }
    }
    if (isPush) {
        newArr.push({val: arr[i], count: 1});
    } else {
        isPush = true;
    }
}
console.log(newArr);
2. es6
var arr = ["2", 1, 5, 4, 7, "9", 4, 1, "2", 6, 8, 2];
var newArr = arr.reduce((arrs, cv) => {
    const found = arrs.find(it => it[0] === cv);
    if (found) {
        found[1] += 1;
    } else {
        arrs.push([cv, 1]);
    }
    return arrs;
}, []);
console.log(newArr);
字符串各個字符的出現(xiàn)次數(shù)
var str = "abdcsdwdaoprr";
for (var i = 0, len = str.length, obj = {}; i < len; i++) {
    if (obj[str[i]]) {
        obj[str[i]]++;
    } else {
        obj[str[i]] = 1;
    }
}
console.log(obj);
獲取地址鏈接的各個參數(shù)
var url = "https://www.google.com.hk/search?safe=strict&ei=M_u5WvLZO4bzUrfpn_AJ&q=js%9F%&oq=js%E7%BB&gs_l=psy-ab";
var search = url.substring(url.indexOf("?")+1);
    var tmpArr = search.split("&");
    var urlParmObj = {};
    if (tmpArr.length > 0 && tmpArr[0] != "") {
            for (var i = 0, len = tmpArr.length; i < len; i++) {
                    var tmp = tmpArr[i].split("=");
                    urlParmObj[tmp[0]] = tmp[1];
            }
    }
    console.log(urlParmObj);
es6 實踐
var arr = [1,2,3,4,5];
const param = arr.find(it => it === 5);
param += 1;
console.log(arr);
更多其它內(nèi)容請查看