如何在JavaScript中执行关联数组/哈希
我需要使用JavaScript存储一些统计数据,就像在C#中一样:如何在JavaScript中执行关联数组/哈希,javascript,dictionary,hashtable,Javascript,Dictionary,Hashtable,我需要使用JavaScript存储一些统计数据,就像在C#中一样: 字典统计; 统计数字[“Foo”]=10; 统计数字[“咕”]=统计数字[“咕”]+1; 统计数据。添加(“动物园”,1); JavaScript中是否有哈希表或类似于字典的东西? 我怎么能以这种方式存储值呢?因为JavaScript中的每个对象的行为都类似于哈希表,而且通常都是作为哈希表实现的,所以我同意 var hashSweetHashTable = {}; 除非你有特殊的理由不这样做,否则就使用普通对象。可以使用哈希
字典统计;
统计数字[“Foo”]=10;
统计数字[“咕”]=统计数字[“咕”]+1;
统计数据。添加(“动物园”,1);
JavaScript中是否有哈希表
或类似于字典的东西?
我怎么能以这种方式存储值呢?因为JavaScript中的每个对象的行为都类似于哈希表,而且通常都是作为哈希表实现的,所以我同意
var hashSweetHashTable = {};
除非你有特殊的理由不这样做,否则就使用普通对象。可以使用哈希表样式语法引用JavaScript中的对象属性:
var hashtable = {};
hashtable.foo = "bar";
hashtable['bar'] = "foo";
foo
和bar
元素现在都可以引用为:
hashtable['foo'];
hashtable['bar'];
// Or
hashtable.foo;
hashtable.bar;
当然,这意味着您的键必须是字符串。如果它们不是字符串,则会在内部转换为字符串,因此可能仍然有效。您的里程数可能会有所不同。请使用
关联数组:简单地说,关联数组使用字符串而不是整数作为索引
使用创建对象
var dictionary = {};
JavaScript允许您使用以下语法向对象添加属性:
var point = { x:3, y:2 };
point["x"] // returns 3
point.y // returns 2
同样的另一种语法是:
Object["yourProperty"] = value;
如果可以,还可以使用以下语法创建键到值对象映射:
var point = { x:3, y:2 };
point["x"] // returns 3
point.y // returns 2
可以使用for..in循环构造遍历关联数组,如下所示
如果您来自面向对象语言,您应该检查。如果您要求您的键是任何对象而不仅仅是字符串,那么您可以使用my。函数HashTable(){
这个长度=0;
this.items=新数组();
对于(变量i=0;i
var HashTable=function(){
这个。_存储=[];
这个。_count=0;
这一限制=8;
}
HashTable.prototype.insert=函数(键,值){
//通过传递
//它是通过我们的散列函数实现的
var index=this.hashFunc(key,this.\u limit);
//在中检索此特定索引处的存储桶
//我们的仓库,如果有的话
//[k,v],[k,v],[k,v],[k,v],[k,v]][[k,v]]
var bucket=此存储[索引]
//是否存在一个桶或我们得到未定义
//当试图检索所述索引时?
如果(!桶){
//创建桶
var bucket=[];
//将bucket插入哈希表
此._存储[索引]=存储桶;
}
var覆盖=false;
//现在遍历我们的bucket,看看是否存在任何冲突
//bucket中的键值对。如果有,请覆盖它们。
对于(变量i=0;i此._限制*0.75){
此.resize(此.u限制*2);
}
}
归还这个;
};
HashTable.prototype.remove=函数(键){
var index=this.hashFunc(key,this.\u limit);
var bucket=此存储[索引];
如果(!桶){
返回null;
}
//在桶上迭代
对于(变量i=0;i hash=(hash所有现代浏览器都支持JavaScript对象。有几个原因使使用映射优于对象:
- 对象有一个原型,因此地图中有默认关键点
- 对象的键是字符串,它们可以是贴图的任何值
- 你可以得到这个尺寸
var point = { x:3, y:2 };
point["x"] // returns 3
point.y // returns 2
for(var key in Object.keys(dict)){
var value = dict[key];
/* use key/value for intended purpose */
}
var associativeArray = {};
associativeArray["one"] = "First";
associativeArray["two"] = "Second";
associativeArray["three"] = "Third";
function HashTable() {
this.length = 0;
this.items = new Array();
for (var i = 0; i < arguments.length; i += 2) {
if (typeof (arguments[i + 1]) != 'undefined') {
this.items[arguments[i]] = arguments[i + 1];
this.length++;
}
}
this.removeItem = function (in_key) {
var tmp_previous;
if (typeof (this.items[in_key]) != 'undefined') {
this.length--;
var tmp_previous = this.items[in_key];
delete this.items[in_key];
}
return tmp_previous;
}
this.getItem = function (in_key) {
return this.items[in_key];
}
this.setItem = function (in_key, in_value) {
var tmp_previous;
if (typeof (in_value) != 'undefined') {
if (typeof (this.items[in_key]) == 'undefined') {
this.length++;
} else {
tmp_previous = this.items[in_key];
}
this.items[in_key] = in_value;
}
return tmp_previous;
}
this.hasItem = function (in_key) {
return typeof (this.items[in_key]) != 'undefined';
}
this.clear = function () {
for (var i in this.items) {
delete this.items[i];
}
this.length = 0;
}
}
var HashTable = function() {
this._storage = [];
this._count = 0;
this._limit = 8;
}
HashTable.prototype.insert = function(key, value) {
// Create an index for our storage location by passing
// it through our hashing function
var index = this.hashFunc(key, this._limit);
// Retrieve the bucket at this particular index in
// our storage, if one exists
//[[ [k,v], [k,v], [k,v] ] , [ [k,v], [k,v] ] [ [k,v] ] ]
var bucket = this._storage[index]
// Does a bucket exist or do we get undefined
// when trying to retrieve said index?
if (!bucket) {
// Create the bucket
var bucket = [];
// Insert the bucket into our hashTable
this._storage[index] = bucket;
}
var override = false;
// Now iterate through our bucket to see if there are any conflicting
// key value pairs within our bucket. If there are any, override them.
for (var i = 0; i < bucket.length; i++) {
var tuple = bucket[i];
if (tuple[0] === key) {
// Override value stored at this key
tuple[1] = value;
override = true;
}
}
if (!override) {
// Create a new tuple in our bucket.
// Note that this could either be the new empty bucket we created above
// or a bucket with other tupules with keys that are different than
// the key of the tuple we are inserting. These tupules are in the same
// bucket because their keys all equate to the same numeric index when
// passing through our hash function.
bucket.push([key, value]);
this._count++
// Now that we've added our new key/val pair to our storage
// let's check to see if we need to resize our storage
if (this._count > this._limit * 0.75) {
this.resize(this._limit * 2);
}
}
return this;
};
HashTable.prototype.remove = function(key) {
var index = this.hashFunc(key, this._limit);
var bucket = this._storage[index];
if (!bucket) {
return null;
}
// Iterate over the bucket
for (var i = 0; i < bucket.length; i++) {
var tuple = bucket[i];
// Check to see if key is inside bucket
if (tuple[0] === key) {
// If it is, get rid of this tuple
bucket.splice(i, 1);
this._count--;
if (this._count < this._limit * 0.25) {
this._resize(this._limit / 2);
}
return tuple[1];
}
}
};
HashTable.prototype.retrieve = function(key) {
var index = this.hashFunc(key, this._limit);
var bucket = this._storage[index];
if (!bucket) {
return null;
}
for (var i = 0; i < bucket.length; i++) {
var tuple = bucket[i];
if (tuple[0] === key) {
return tuple[1];
}
}
return null;
};
HashTable.prototype.hashFunc = function(str, max) {
var hash = 0;
for (var i = 0; i < str.length; i++) {
var letter = str[i];
hash = (hash << 5) + letter.charCodeAt(0);
hash = (hash & hash) % max;
}
return hash;
};
HashTable.prototype.resize = function(newLimit) {
var oldStorage = this._storage;
this._limit = newLimit;
this._count = 0;
this._storage = [];
oldStorage.forEach(function(bucket) {
if (!bucket) {
return;
}
for (var i = 0; i < bucket.length; i++) {
var tuple = bucket[i];
this.insert(tuple[0], tuple[1]);
}
}.bind(this));
};
HashTable.prototype.retrieveAll = function() {
console.log(this._storage);
//console.log(this._limit);
};
/******************************TESTS*******************************/
var hashT = new HashTable();
hashT.insert('Alex Hawkins', '510-599-1930');
//hashT.retrieve();
//[ , , , [ [ 'Alex Hawkins', '510-599-1930' ] ] ]
hashT.insert('Boo Radley', '520-589-1970');
//hashT.retrieve();
//[ , [ [ 'Boo Radley', '520-589-1970' ] ], , [ [ 'Alex Hawkins', '510-599-1930' ] ] ]
hashT.insert('Vance Carter', '120-589-1970').insert('Rick Mires', '520-589-1970').insert('Tom Bradey', '520-589-1970').insert('Biff Tanin', '520-589-1970');
//hashT.retrieveAll();
/*
[ ,
[ [ 'Boo Radley', '520-589-1970' ],
[ 'Tom Bradey', '520-589-1970' ] ],
,
[ [ 'Alex Hawkins', '510-599-1930' ],
[ 'Rick Mires', '520-589-1970' ] ],
,
,
[ [ 'Biff Tanin', '520-589-1970' ] ] ]
*/
// Override example (Phone Number Change)
//
hashT.insert('Rick Mires', '650-589-1970').insert('Tom Bradey', '818-589-1970').insert('Biff Tanin', '987-589-1970');
//hashT.retrieveAll();
/*
[ ,
[ [ 'Boo Radley', '520-589-1970' ],
[ 'Tom Bradey', '818-589-1970' ] ],
,
[ [ 'Alex Hawkins', '510-599-1930' ],
[ 'Rick Mires', '650-589-1970' ] ],
,
,
[ [ 'Biff Tanin', '987-589-1970' ] ] ]
*/
hashT.remove('Rick Mires');
hashT.remove('Tom Bradey');
//hashT.retrieveAll();
/*
[ ,
[ [ 'Boo Radley', '520-589-1970' ] ],
,
[ [ 'Alex Hawkins', '510-599-1930' ] ],
,
,
[ [ 'Biff Tanin', '987-589-1970' ] ] ]
*/
hashT.insert('Dick Mires', '650-589-1970').insert('Lam James', '818-589-1970').insert('Ricky Ticky Tavi', '987-589-1970');
hashT.retrieveAll();
/* NOTICE HOW THE HASH TABLE HAS NOW DOUBLED IN SIZE UPON REACHING 75% CAPACITY, i.e. 6/8. It is now size 16.
[,
,
[ [ 'Vance Carter', '120-589-1970' ] ],
[ [ 'Alex Hawkins', '510-599-1930' ],
[ 'Dick Mires', '650-589-1970' ],
[ 'Lam James', '818-589-1970' ] ],
,
,
,
,
,
[ [ 'Boo Radley', '520-589-1970' ],
[ 'Ricky Ticky Tavi', '987-589-1970' ] ],
,
,
,
,
[ [ 'Biff Tanin', '987-589-1970' ] ] ]
*/
console.log(hashT.retrieve('Lam James')); // 818-589-1970
console.log(hashT.retrieve('Dick Mires')); // 650-589-1970
console.log(hashT.retrieve('Ricky Ticky Tavi')); //987-589-1970
console.log(hashT.retrieve('Alex Hawkins')); // 510-599-1930
console.log(hashT.retrieve('Lebron James')); // null
var myMap = new Map();
var keyObj = {},
keyFunc = function () {},
keyString = "a string";
myMap.set(keyString, "value associated with 'a string'");
myMap.set(keyObj, "value associated with keyObj");
myMap.set(keyFunc, "value associated with keyFunc");
myMap.size; // 3
myMap.get(keyString); // "value associated with 'a string'"
myMap.get(keyObj); // "value associated with keyObj"
myMap.get(keyFunc); // "value associated with keyFunc"
Dictionary<string,int> dictionary = new Dictionary<string,int>();
dictionary.add("sample1", 1);
dictionary.add("sample2", 2);
var dictionary = new Dictionary<string, int> {
{"sample1", 1},
{"sample2", 2}
};
var dictionary = {
"sample1": 1,
"sample2": 2
}
if (dictionary.hasOwnProperty("sample1"))
console.log("sample1 key found and its value is"+ dictionary["sample1"]);
function Hashtable() {
this._map = new Map();
this._indexes = new Map();
this._keys = [];
this._values = [];
this.put = function(key, value) {
var newKey = !this.containsKey(key);
this._map.set(key, value);
if (newKey) {
this._indexes.set(key, this.length);
this._keys.push(key);
this._values.push(value);
}
};
this.remove = function(key) {
if (!this.containsKey(key))
return;
this._map.delete(key);
var index = this._indexes.get(key);
this._indexes.delete(key);
this._keys.splice(index, 1);
this._values.splice(index, 1);
};
this.indexOfKey = function(key) {
return this._indexes.get(key);
};
this.indexOfValue = function(value) {
return this._values.indexOf(value) != -1;
};
this.get = function(key) {
return this._map.get(key);
};
this.entryAt = function(index) {
var item = {};
Object.defineProperty(item, "key", {
value: this.keys[index],
writable: false
});
Object.defineProperty(item, "value", {
value: this.values[index],
writable: false
});
return item;
};
this.clear = function() {
var length = this.length;
for (var i = 0; i < length; i++) {
var key = this.keys[i];
this._map.delete(key);
this._indexes.delete(key);
}
this._keys.splice(0, length);
};
this.containsKey = function(key) {
return this._map.has(key);
};
this.containsValue = function(value) {
return this._values.indexOf(value) != -1;
};
this.forEach = function(iterator) {
for (var i = 0; i < this.length; i++)
iterator(this.keys[i], this.values[i], i);
};
Object.defineProperty(this, "length", {
get: function() {
return this._keys.length;
}
});
Object.defineProperty(this, "keys", {
get: function() {
return this._keys;
}
});
Object.defineProperty(this, "values", {
get: function() {
return this._values;
}
});
Object.defineProperty(this, "entries", {
get: function() {
var entries = new Array(this.length);
for (var i = 0; i < entries.length; i++)
entries[i] = this.entryAt(i);
return entries;
}
});
}