修改IE不兼容MAP()的问题,自定义实现JavaScript的Map对象

发布时间:2018-01-07 10:06  浏览次数:465

由于IE8及以下版本不支持Map对象,本文为程序猿们提供了有效的解决方法。

本文重写了Map对象,实现了常用的set, get, put, clear, remove, delete, forEach, has, containsKey, isEmpty, size 等方法,使用和声明的方试和正常声明Map对象一样:

var map = new Map();

只需将下面代码拷入<script type="text/javascript"></script>中即可。

function Map() {
        this.elements = new Array();
        // 获取Map元素个数
        this.size = function() {
            return this.elements.length;
        },
        // 判断Map是否为空
        this.isEmpty = function() {
            return (this.elements.length < 1);
        },
        // 删除Map所有元素
        this.clear = function() {
            this.elements = new Array();
        },
        // 向Map中增加元素(key, value)
        this.put = function(_key, _value) {
            if (this.containsKey(_key) == true) {
                if (this.containsValue(_value)) {
                    if (this.remove(_key) == true) {
                        this.elements.push({
                            key : _key,
                            value : _value
                        });
                    }
                } else {
                    this.elements.push({
                        key : _key,
                        value : _value
                    });
                }
            } else {
                this.elements.push({
                    key : _key,
                    value : _value
                });
            }
        },
        // 向Map中增加元素(key, value)
        this.set = function(_key, _value) {
            if (this.containsKey(_key) == true) {
                if (this.containsValue(_value)) {
                    if (this.remove(_key) == true) {
                        this.elements.push({
                            key : _key,
                            value : _value
                        });
                    }
                } else {
                    this.elements.push({
                        key : _key,
                        value : _value
                    });
                }
            } else {
                this.elements.push({
                    key : _key,
                    value : _value
                });
            }
        },
        // 删除指定key的元素,成功返回true,失败返回false
        this.remove = function(_key) {
            var bln = false;
            try {
                for (i = 0; i < this.elements.length; i++) {
                    if (this.elements[i].key == _key) {
                        this.elements.splice(i, 1);
                        return true;
                    }
                }
            } catch (e) {
                bln = false;
            }
            return bln;
        },

        // 删除指定key的元素,成功返回true,失败返回false
        this.delete = function(_key) {
            var bln = false;
            try {
                for (i = 0; i < this.elements.length; i++) {
                    if (this.elements[i].key == _key) {
                        this.elements.splice(i, 1);
                        return true;
                    }
                }
            } catch (e) {
                bln = false;
            }
            return bln;
        },
        
        // 获取指定key的元素值value,失败返回null
        this.get = function(_key) {
            try {
                for (i = 0; i < this.elements.length; i++) {
                    if (this.elements[i].key == _key) {
                        return this.elements[i].value;
                    }
                }
            } catch (e) {
                return null;
            }
        },

        // set指定key的元素值value
        this.setValue = function(_key, _value) {
            var bln = false;
            try {
                for (i = 0; i < this.elements.length; i++) {
                    if (this.elements[i].key == _key) {
                        this.elements[i].value = _value;
                        return true;
                    }
                }
            } catch (e) {
                bln = false;
            }
            return bln;
        },

        // 获取指定索引的元素(使用element.key,element.value获取key和value),失败返回null
        this.element = function(_index) {
            if (_index < 0 || _index >= this.elements.length) {
                return null;
            }
            return this.elements[_index];
        },

        // 判断Map中是否含有指定key的元素
        this.containsKey = function(_key) {
            var bln = false;
            try {
                for (i = 0; i < this.elements.length; i++) {
                    if (this.elements[i].key == _key) {
                        bln = true;
                    }
                }
            } catch (e) {
                bln = false;
            }
            return bln;
        },

        // 判断Map中是否含有指定key的元素
        this.has = function(_key) {
            var bln = false;
            try {
                for (i = 0; i < this.elements.length; i++) {
                    if (this.elements[i].key == _key) {
                        bln = true;
                    }
                }
            } catch (e) {
                bln = false;
            }
            return bln;
        },
        
        // 判断Map中是否含有指定value的元素
        this.containsValue = function(_value) {
            var bln = false;
            try {
                for (i = 0; i < this.elements.length; i++) {
                    if (this.elements[i].value == _value) {
                        bln = true;
                    }
                }
            } catch (e) {
                bln = false;
            }
            return bln;
        },

        // 获取Map中所有key的数组(array)
        this.keys = function() {
            var arr = new Array();
            for (i = 0; i < this.elements.length; i++) {
                arr.push(this.elements[i].key);
            }
            return arr;
        },

        // 获取Map中所有value的数组(array)
        this.values = function() {
            var arr = new Array();
            for (i = 0; i < this.elements.length; i++) {
                arr.push(this.elements[i].value);
            }
            return arr;
        };
        
        /**
        * map遍历数组
        * @param callback [function] 回调函数;
        * @param context [object] 上下文;
        */
        this.forEach = function forEach(callback,context){
            context = context || window;
            
            //IE6-8下自己编写回调函数执行的逻辑
            var newAry = new Array();
            for(var i = 0; i < this.elements.length;i++) {
                if(typeof  callback === 'function') {
                    var val = callback.call(context,this.elements[i].value,this.elements[i].key,this.elements);
                    newAry.push(this.elements[i].value);
                }
            }
            return newAry;
        }

    }


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