javaScript資料結構之集合

01 集合

集合是由一組無序且唯一的項組成。

02 建立一個集合

在es6中已經有Set，大概用法如下：

var set = new Set([1,2,3,1]);
set.add(5);
console.log(set);

我們寫一個Set

function Set(arr) {
    var _item = {};

    (function Set(list){
        if(list) {
            for(var i = 0; i < list.length; i++) {
                _item[list[i]] = list[i];
            }
        }
    })(arr);

    this
 
.has = function(value) {
        return value in _item;
    };

    this.add = function(value) {
        var isSucc = false;
        if (!this.has(value)) {
            _item[value] = value;
            isSucc = true;
        }
        return isSucc;
    };

    this.remove = function(value) {
        var
 
 isSucc = false;
        if(!this.has(value)) {
            delete _item[value];
            isSucc = true;
        };
        return true;
    };

    this.clear = function() {
        _item = {};
    };

    this.size = function() {
        var count = 0;
        for(var attr in _item) {
            if
 
(_item.hasOwnProperty(attr)) {
                ++count;
            };
        }
        return count;
        //return Object.keys(_item).length;
    };

    this.values = function() {
        var keys = [];
        for(var attr in _item) {
            if(_item.hasOwnProperty(attr)) {
                keys.push(attr);
            };
        }
        return keys;
        //return Object.keys(_item);
    };

    this.forEach = function(fn) {
        this.values().forEach(fn);
    }
}
var s = new Set([1,23,4,4,1]);
s.add(5);
console.log(s);