1、輸入一個值，返回其資料型別

function type(para) {
    return Object.prototype.toString.call(para)
}

2、陣列去重

function unique1(arr) {
    return [...new Set(arr)]
}

function unique2(arr) {
    var obj = {};
    return arr.filter(ele => {
        if (!obj[ele]) {
            obj[ele] = true;
            return true;
        }
    })
}

function unique3(arr) {
    var result = [];
    arr.forEach(ele => {
        if (result.indexOf(ele) == -1) {
            result.push(ele)
        }
    })
    return result;
}
 

3、字串去重

String.prototype.unique = function () {
    var obj = {},
        str = '',
        len = this.length;
    for (var i = 0; i < len; i++) {
        if (!obj[this[i]]) {
            str += this[i];
            obj[this[i]] = true;
        }
    }
    return str;
}

//去除連續的字串
function uniq(str) {
    return str.replace(/(\w)\1+/g, '$1')
}
 

4、深拷貝 淺拷貝

//深克隆（深克隆不考慮函式）
function deepClone(obj, result) {
    var result = result || {};
    for (var prop in obj) {
        if (obj.hasOwnProperty(prop)) {
            if (typeof obj[prop] == 'object' && obj[prop] !== null) {
                // 引用值(obj/array)且不為null
                if (Object.prototype.toString.call(obj[prop]) == '[object Object]') {
                    // 物件
                    result[prop] = {};
                } else {
                    // 陣列
                    result[prop] = [];
                }
                deepClone(obj[prop], result[prop])
    } else {
        // 原始值或func
        result[prop] = obj[prop]
    }
  }
}
return result;
}

// 深淺克隆是針對引用值
function deepClone(target) {
    if (typeof (target) !== 'object') {
        return target;
    }
    var result;
    if (Object.prototype.toString.call(target) == '[object Array]') {
        // 陣列
        result = []
    } else {
        // 物件
        result = {};
    }
    for (var prop in target) {
        if (target.hasOwnProperty(prop)) {
            result[prop] = deepClone(target[prop])
        }
    }
    return result;
}
// 無法複製函式
var o1 = JSON.parse(JSON.stringify(obj1));
 

5、reverse底層原理和擴充套件

// 改變原陣列
Array.prototype.myReverse = function () {
    var len = this.length;
    for (var i = 0; i < len; i++) {
        var temp = this[i];
        this[i] = this[len - 1 - i];
        this[len - 1 - i] = temp;
    }
    return this;
}

6、聖盃模式的繼承

function inherit(Target, Origin) {
    function F() {};
    F.prototype = Origin.prototype;
    Target.prototype = new F();
    Target.prototype.constructor = Target;
    // 最終的原型指向
    Target.prop.uber = Origin.prototype;
}

7、找出字串中第一次只出現一次的字母

String.prototype.firstAppear = function () {
    var obj = {},
        len = this.length;
    for (var i = 0; i < len; i++) {
        if (obj[this[i]]) {
            obj[this[i]]++;
        } else {
            obj[this[i]] = 1;
        }
    }
    for (var prop in obj) {
       if (obj[prop] == 1) {
         return prop;
       }
    }
}

8、找元素的第n級父元素

function parents(ele, n) {
    while (ele && n) {
        ele = ele.parentElement ? ele.parentElement : ele.parentNode;
        n--;
    }
    return ele;
}

9、 返回元素的第n個兄弟節點

function retSibling(e, n) {
    while (e && n) {
        if (n > 0) {
            if (e.nextElementSibling) {
                e = e.nextElementSibling;
            } else {
                for (e = e.nextSibling; e && e.nodeType !== 1; e = e.nextSibling);
            }
            n--;
        } else {
            if (e.previousElementSibling) {
                e = e.previousElementSibling;
            } else {
                for (e = e.previousElementSibling; e && e.nodeType !== 1; e = e.previousElementSibling);
            }
            n++;
        }
    }
    return e;
}

10、判斷元素有沒有子元素

function hasChildren(e) {
    var children = e.childNodes,
        len = children.length;
    for (var i = 0; i < len; i++) {
        if (children[i].nodeType === 1) {
            return true;
        }
    }
    return false;
}