带有名称的 JavaScript 字典

JavaScript dictionary with names

提问by Kiran

I want to create a dictionary in javascript like the following:

我想在 javascript 中创建一个字典，如下所示：

myMappings = [
{ "Name":10%},
{ "Phone":10%},
{ "Address":50%},
{ "Zip":10%},
{ "Comments":20%}
]

I want to populate an html table later and want to set the titles of table to the first column of myMappings and the width of columns to the second. As I am new to JS, having trouble finding the clean way. Can some pls suggest?

我想稍后填充一个 html 表，并希望将表的标题设置为 myMappings 的第一列，将列的宽度设置为第二列。因为我是 JS 的新手，所以很难找到干净的方法。一些请建议？

Thanks

谢谢

回答by Lev

Another approach would be to have an array of objects, with each individual object holding the properties of a column. This slightly changes the structure of "myMappings", but makes it easy to work with:

另一种方法是拥有一个对象数组，每个单独的对象都保存一列的属性。这稍微改变了“myMappings”的结构，但使其易于使用：

var myMappings = [
    { title: "Name", width: "10%" },
    { title: "Phone", width: "10%" },
    { title: "Address", width: "50%" },
    { title: "Zip", width: "10%" },
    { title: "Comments", width: "20%" }
];

Then you could easily iterate through all your "columns" with a for loop:

然后，您可以使用 for 循环轻松遍历所有“列”：

for (var i = 0; i < myMappings.length; i += 1) {
    // myMappings[i].title ...
    // myMappings[i].width ...
}

回答by David Tang

The main problem I see with what you have is that it's difficult to loop through, for populating a table.

我所看到的主要问题是很难循环，以填充表格。

Simply use an array of arrays:

只需使用数组数组：

var myMappings = [
    ["Name", "10%"], // Note the quotes around "10%"
    ["Phone", "10%"],
    // etc..
];

... which simplifies access:

...这简化了访问：

myMappings[0][0]; // column name
myMappings[0][1]; // column width

---

---

Alternatively:

或者：

var myMappings = {
    names: ["Name", "Phone", etc...],
    widths: ["10%", "10%", etc...]
};

And access with:

并通过以下方式访问：

myMappings.names[0];
myMappings.widths[0];

回答by Jason

Are you trying to use a JSON object?

您是否正在尝试使用 JSON 对象？

var myMappings = { "name": "10%", "phone": "10%", "address": "50%", etc.. }

To access:

访问：

myMappings.name;
myMappings.phone;
etc..

回答by Jani Hyyti?inen

An object technically is adictionary.

从技术上讲，对象是字典。

var myMappings = {
    mykey1: 'myValue',
    mykey2: 'myValue'
};

var myVal = myMappings['myKey1'];

alert(myVal); // myValue

You can even loop through one.

你甚至可以循环一个。

for(var key in myMappings) {
    var myVal = myMappings[key];
    alert(myVal);
}

There is no reason what so ever to reinvent the wheel. And of course, assignment goes like:

没有理由重新发明轮子。当然，分配是这样的：

myMappings['mykey3'] = 'my value';

And ContainsKey:

并包含密钥：

if (myMappings.hasOwnProperty('myKey3')) {
    alert('key already exists!');
}

I suggest you follow this http://javascriptissexy.com/how-to-learn-javascript-properly/

我建议你按照这个http://javascriptissexy.com/how-to-learn-javascript-properly/

回答by 0e4ef622

Try:

尝试：

var myMappings = {"Name":"10%",
"Phone":"10%",
"Address":"50%",
"Zip":"10%",
"Comments":"20%"}
//access like this
myMappings["Name"] //returns "10%"
myMappings.Name //same thing as above
//to loop through...
for(var title in myMappings){
  //do whatever with myMappings[title]
}

回答by Vaibhav

Edit>> Good news, here is now an easier, native and more efficient way of emulating a dict in JS:Also exploit that JS is weakly typed. Rather type inference. Anyway..

编辑>> 好消息，这里现在是一种在 JS 中模拟 dict 的更简单、本机和更有效的方法：同时利用 JS 是弱类型的。而是类型推断。反正..

Here's how (an excerpt from Google Chrome's console):

方法如下（摘自 Google Chrome 的控制台）：

var myDict = {};

myDict.one = 1;
1

myDict.two = 2;
2

if (myDict.hasOwnProperty('three'))
{
  console.log(myDict.two);
}
else
{
  console.log('Key does not exist!');
}
Key does not exist! VM361:8

if (myDict.hasOwnProperty('two'))
{
  console.log(myDict.two);
}
else
{
  console.log('Key does not exist!');
}
2 VM362:4

Object.keys(myDict);
["one", "two"]

delete(myDict.two);
true

myDict.hasOwnProperty('two');
false

myDict.two
undefined

myDict.one
1

回答by John Giotta

I suggest not using an array unless you have multiple objects to consider. There isn't anything wrong this statement.

我建议不要使用数组，除非你有多个对象要考虑。这个说法没有任何问题。

var myMappings = {
    "Name":0.1,
    "Phone":0.1,
    "Address":0.5,
    "Zip":0.1,
    "Comments":0.2
};
for (var col in myMappings) {
    alert((myMappings[col] * 100) + "%");
}

回答by Dan Ricker

Here's a dictionary that will take any type of Key as long as the toString() property returns unique values. The dictionary uses anything as the value for the key value pair.

这是一个字典，只要 toString() 属性返回唯一值，它就会采用任何类型的 Key。字典使用任何东西作为键值对的值。

See http://www.codeproject.com/Articles/684815/Would-JavaScript-Benefit-from-a-Dictionary-Object

请参阅http://www.codeproject.com/Articles/684815/Would-JavaScript-Benefit-from-a-Dictionary-Object

To use the dictionary as is:

要按原样使用字典：

var dictFact = new Dict();
var myDict = dictFact.New();
myDict.addOrUpdate("key1", "Value1");
myDict.addOrUpdate("key2", "Value2");
myDict.addOrUpdate("keyN", "ValueN");

Dictionary Code Below:

字典代码如下：

/*
* Dictionary Factory Object
* Holds common object functions. similar to V-Table
* this.New() used to create new dictionary objects
* Uses Object.defineProperties so won't work on older browsers.
* Browser Compatibility (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/defineProperties)
*      Firefox (Gecko) 4.0 (2), Chrome 5, IE 9, Opera 11.60, Safari 5
*/
function Dict() {

    /*
    * Create a new Dictionary
    */
    this.New = function () {
        return new dict();
    };

    /*
    * Return argument f if it is a function otherwise return undefined
    */
    function ensureF(f) {
        if (isFunct(f)) {
            return f;
        }
    }

    function isFunct(f) {
        return (typeof f == "function");
    }

    /*
    * Add a "_" as first character just to be sure valid property name
    */
    function makeKey(k) {
        return "_" + k;
    };

    /*
    * Key Value Pair object - held in array
    */
    function newkvp(key, value) {
        return {
            key: key,
            value: value,
            toString: function () { return this.key; },
            valueOf: function () { return this.key; }
        };
    };

    /*
    * Return the current set of keys. 
    */
    function keys(a) {
        // remove the leading "-" character from the keys
        return a.map(function (e) { return e.key.substr(1); });
        // Alternative: Requires Opera 12 vs. 11.60
        // -- Must pass the internal object instead of the array
        // -- Still need to remove the leading "-" to return user key values
        //    Object.keys(o).map(function (e) { return e.key.substr(1); });
    };

    /*
    * Return the current set of values. 
    */
    function values(a) {
        return a.map(function(e) { return e.value; } );
    };

    /*
    * Return the current set of key value pairs. 
    */
    function kvPs(a) {
        // remove the leading "-" character from the keys
        return a.map(function (e) { return newkvp(e.key.substr(1), e.value); });
    }

    /*
    * Returns true if key exists in the dictionary.
    * k - Key to check (with the leading "_" character) 
    */
    function exists(k, o) {
        return o.hasOwnProperty(k);
    }

    /*
    * Array Map implementation
    */
    function map(a, f) {
        if (!isFunct(f)) { return; }
        return a.map(function (e, i) { return f(e.value, i); });
    }

    /*
    * Array Every implementation
    */
    function every(a, f) {
        if (!isFunct(f)) { return; }
        return a.every(function (e, i) { return f(e.value, i) });
    }

    /*
    * Returns subset of "values" where function "f" returns true for the "value"
    */
    function filter(a, f) {
        if (!isFunct(f)) {return; }
        var ret = a.filter(function (e, i) { return f(e.value, i); });
        // if anything returned by array.filter, then get the "values" from the key value pairs
        if (ret && ret.length > 0) {
            ret = values(ret);
        }
        return ret;
    }

    /*
    * Array Reverse implementation
    */
    function reverse(a, o) {
        a.reverse();
        reindex(a, o, 0);
    }

    /**
    * Randomize array element order in-place.
    * Using Fisher-Yates shuffle algorithm.
    */
    function shuffle(a, o) {
        var j, t;
        for (var i = a.length - 1; i > 0; i--) {
            j = Math.floor(Math.random() * (i + 1));
            t = a[i];
            a[i] = a[j];
            a[j] = t;
        }
        reindex(a, o, 0);
        return a;
    }
    /*
    * Array Some implementation
    */
    function some(a, f) {
        if (!isFunct(f)) { return; }
        return a.some(function (e, i) { return f(e.value, i) });
    }

    /*
    * Sort the dictionary. Sorts the array and reindexes the object.
    * a - dictionary array
    * o - dictionary object
    * sf - dictionary default sort function (can be undefined)
    * f - sort method sort function argument (can be undefined)
    */
    function sort(a, o, sf, f) {
        var sf1 = f || sf; // sort function  method used if not undefined
        // if there is a customer sort function, use it
        if (isFunct(sf1)) {
            a.sort(function (e1, e2) { return sf1(e1.value, e2.value); });
        }
        else {
            // sort by key values
            a.sort();
        }
        // reindex - adds O(n) to perf
        reindex(a, o, 0);
        // return sorted values (not entire array)
        // adds O(n) to perf
        return values(a);
    };

    /*
    * forEach iteration of "values"
    *   uses "for" loop to allow exiting iteration when function returns true 
    */
    function forEach(a, f) {
        if (!isFunct(f)) { return; }
        // use for loop to allow exiting early and not iterating all items
        for(var i = 0; i < a.length; i++) {
            if (f(a[i].value, i)) { break; }
        }
    };

    /*
    * forEachR iteration of "values" in reverse order
    *   uses "for" loop to allow exiting iteration when function returns true 
    */
    function forEachR(a, f) {
        if (!isFunct(f)) { return; }
        // use for loop to allow exiting early and not iterating all items
        for (var i = a.length - 1; i > -1; i--) {
            if (f(a[i].value, i)) { break; }
        }
    }

    /*
    * Add a new Key Value Pair, or update the value of an existing key value pair
    */
    function add(key, value, a, o, resort, sf) {
        var k = makeKey(key);
        // Update value if key exists
        if (exists(k, o)) {
            a[o[k]].value = value;
        }
        else {
            // Add a new Key value Pair
            var kvp = newkvp(k, value);
            o[kvp.key] = a.length;
            a.push(kvp);
        }
        // resort if requested
        if (resort) { sort(a, o, sf); }
    };

    /*
    * Removes an existing key value pair and returns the "value" If the key does not exists, returns undefined
    */
    function remove(key, a, o) {
        var k = makeKey(key);
        // return undefined if the key does not exist
        if (!exists(k, o)) { return; }
        // get the array index
        var i = o[k];
        // get the key value pair
        var ret = a[i];
        // remove the array element
        a.splice(i, 1);
        // remove the object property
        delete o[k];
        // reindex the object properties from the remove element to end of the array
        reindex(a, o, i);
        // return the removed value
        return ret.value;
    };

    /*
    * Returns true if key exists in the dictionary.
    * k - Key to check (without the leading "_" character) 
    */
    function keyExists(k, o) {
        return exists(makeKey(k), o);
    };

    /*
    * Returns value assocated with "key". Returns undefined if key not found
    */
    function item(key, a, o) {
        var k = makeKey(key);
        if (exists(k, o)) {
            return a[o[k]].value;
        }
    }

    /*
    * changes index values held by object properties to match the array index location
    * Called after sorting or removing
    */
    function reindex(a, o, i){
        for (var j = i; j < a.length; j++) {
            o[a[j].key] = j;
        }
    }

    /*
    * The "real dictionary"
    */
    function dict() {
        var _a = [];
        var _o = {};
        var _sortF;

        Object.defineProperties(this, {
            "length": { get: function () { return _a.length; }, enumerable: true },
            "keys": { get: function() { return keys(_a); }, enumerable: true },
            "values": { get: function() { return values(_a); }, enumerable: true },
            "keyValuePairs": { get: function() { return kvPs(_a); }, enumerable: true},
            "sortFunction": { get: function() { return _sortF; }, set: function(funct) { _sortF = ensureF(funct); }, enumerable: true }
        });

        // Array Methods - Only modification to not pass the actual array to the callback function
        this.map = function(funct) { return map(_a, funct); };
        this.every = function(funct) { return every(_a, funct); };
        this.filter = function(funct) { return filter(_a, funct); };
        this.reverse = function() { reverse(_a, _o); };
        this.shuffle = function () { return shuffle(_a, _o); };
        this.some = function(funct) { return some(_a, funct); };
        this.sort = function(funct) { return sort(_a, _o, _sortF, funct); };

        // Array Methods - Modified aborts when funct returns true.
        this.forEach = function (funct) { forEach(_a, funct) };

        // forEach in reverse order
        this.forEachRev = function (funct) { forEachR(_a, funct) };

        // Dictionary Methods
        this.addOrUpdate = function(key, value, resort) { return add(key, value, _a, _o, resort, _sortF); };
        this.remove = function(key) { return remove(key, _a, _o); };
        this.exists = function(key) { return keyExists(key, _o); };
        this.item = function(key) { return item(key, _a, _o); };
        this.get = function (index) { if (index > -1 && index < _a.length) { return _a[index].value; } } ,
        this.clear = function() { _a = []; _o = {}; };

        return this;
    }


    return this;
}