有像python这样的javascript中的字典吗？

Question

我需要在这样的javascript中制作字典

我不记得确切的符号,但它是这样的:

states_dictionary={ CT=[alex,harry], AK=[liza,alex], TX=[fred, harry] ........ }

在javascript中有这样的东西吗？

Answer 1

这是一个老帖子,但我认为无论如何我应该提供一个说明性的答案.

使用JavaScript的对象表示法.像这样:

states_dictionary={ 
     "CT":["alex","harry"], 
     "AK":["liza","alex"], 
     "TX":["fred", "harry"]
};

并访问值:

states_dictionary.AK[0] //which is liza

或者您可以使用JavaScript文字对象表示法,其中键不需要在引号中:

states_dictionary={ 
     CT:["alex","harry"], 
     AK:["liza","alex"], 
     TX:["fred", "harry"]
};

Answer 2

Javascript中没有真正的关联数组.您可以尝试使用对象:

var x = new Object();
x["Key"] = "Value";

但是对于对象,不可能使用典型的数组属性或array.length等方法.至少可以在for-in-loop中访问"对象阵列".

Answer 3

在JS中创建了一个简单的字典:

function JSdict() {
    this.Keys = [];
    this.Values = [];
}

// Check if dictionary extensions aren't implemented yet.
// Returns value of a key
if (!JSdict.prototype.getVal) {
    JSdict.prototype.getVal = function (key) {
        if (key == null) {
            return "Key cannot be null";
        }
        for (var i = 0; i < this.Keys.length; i++) {
            if (this.Keys[i] == key) {
                return this.Values[i];
            }
        }
        return "Key not found!";
    }
}


// Check if dictionary extensions aren't implemented yet.
// Updates value of a key
if (!JSdict.prototype.update) {
    JSdict.prototype.update = function (key, val) {
        if (key == null || val == null) {
            return "Key or Value cannot be null";
        }
        // Verify dict integrity before each operation
        if (keysLength != valsLength) {
            return "Dictionary inconsistent. Keys length don't match values!";
        }
        var keysLength = this.Keys.length;
        var valsLength = this.Values.length;
        var flag = false;
        for (var i = 0; i < keysLength; i++) {
            if (this.Keys[i] == key) {
                this.Values[i] = val;
                flag = true;
                break;
            }
        }
        if (!flag) {
            return "Key does not exist";
        }
    }
}



// Check if dictionary extensions aren't implemented yet.
// Adds a unique key value pair
if (!JSdict.prototype.add) {
    JSdict.prototype.add = function (key, val) {
        // Allow only strings or numbers as keys
        if (typeof (key) == "number" || typeof (key) == "string") {
            if (key == null || val == null) {
                return "Key or Value cannot be null";
            }
            if (keysLength != valsLength) {
                return "Dictionary inconsistent. Keys length don't match values!";
            }
            var keysLength = this.Keys.length;
            var valsLength = this.Values.length;
            for (var i = 0; i < keysLength; i++) {
                if (this.Keys[i] == key) {
                    return "Duplicate keys not allowed!";
                }
            }
            this.Keys.push(key);
            this.Values.push(val);
        }
        else {
            return "Only number or string can be key!";
        }
    }
}

// Check if dictionary extensions aren't implemented yet.
// Removes a key value pair
if (!JSdict.prototype.remove) {
    JSdict.prototype.remove = function (key) {
        if (key == null) {
            return "Key cannot be null";
        }
        if (keysLength != valsLength) {
            return "Dictionary inconsistent. Keys length don't match values!";
        }
        var keysLength = this.Keys.length;
        var valsLength = this.Values.length;
        var flag = false;
        for (var i = 0; i < keysLength; i++) {
            if (this.Keys[i] == key) {
                this.Keys.shift(key);
                this.Values.shift(this.Values[i]);
                flag = true;
                break;
            }
        }
        if (!flag) {
            return "Key does not exist";
        }
    }
}

现在可以使用上面的实现来模拟字典:

var dict = new JSdict();

dict.add(1, "one")

dict.add(1, "one more")
"Duplicate keys not allowed!"

dict.getVal(1)
"one"

dict.update(1, "onne")

dict.getVal(1)
"onne"

dict.remove(1)

dict.getVal(1)
"Key not found!"

这只是一个基本的模拟.它可以通过实现更好的运行时算法来进一步优化,以在至少O(nlogn)时间复杂度或甚至更低的时间内工作.像对数组进行合并/快速排序,然后进行一些B搜索查找.我没有尝试或搜索在JS中映射哈希函数.

此外,JSdict obj的Key和Value可以变成隐私的私有变量.

希望这可以帮助!

编辑>>在实现上述之后,我个人使用JS对象作为开箱即用的关联数组.

但是,我想特别提一下实际证明有助于使其成为方便的哈希表体验的两种方法.

即:dict.hasOwnProperty(键) 和 删除词典[键]

阅读这篇文章作为这个实现/用法的一个很好的资源. 在JavaScript关联数组中动态创建键

谢谢!

Answer 4

我意识到这是一个老问题,但是当你搜索"javascript词典"时它会弹出谷歌,所以我想补充一下上面的答案,在ECMAScript 6中,Map已经引入了官方对象,这是一本字典执行:

var dict = new Map();
dict.set("foo", "bar");

//returns "bar"
dict.get("foo");

与javascript的普通对象不同,它允许任何对象作为键:

var foo = {};
var bar = {};
var dict = new Map();
dict.set(foo, "Foo");
dict.set(bar, "Bar");

//returns "Bar"
dict.get(bar);

//returns "Foo"
dict.get(foo);

//returns undefined, as {} !== foo and {} !== bar
dict.get({});

Answer 5

使用JavaScript对象。您可以访问它们的属性，例如字典中的键。这是JSON的基础。语法类似于Python字典。请参阅：JSON.org