Let us set up a simple class that we'll use to define all these methods on. We'll create a container object to store the hash table and create a display function to display the table. Note that for collision resolution, we'll use chaining.The display function takes each entry (hashed value) in the table and prints all pairs associated with it.ExampleWe'll also create a new class on the prototype to store the key-value pairs.class HashTable {    constructor() {       this.container = [];       // Populate the container with empty arrays       // which can ... Read More

Hash Table is a data structure which stores data in an associative manner. In a hash table, data is stored in an array format, where each data value has its own unique index value. Access to data becomes very fast if we know the index of the desired data.Thus, it becomes a data structure in which insertion and search operations are very fast irrespective of the size of the data. Hash Table uses an array as a storage medium and uses the hash technique to generate an index where an element is to be inserted or is to be located ... Read More

Here is the complete implementation of MyMap class − Exampleclass MyMap {    constructor() {       this.container = {};    }    display() {       console.log(this.container);    }    hasKey(key) {       return key in this.container;    }    put(key, value) {       this.container[key] = value;    }    delete(key) {       if (this.hasKey(key)) {          delete this.container[key];          return true;       }       return false;    }    get(key) {       return this.hasKey(key) ? this.container[key] : undefined;   ... Read More

Here we'll implement a for each function in our class and accept a callback that we can call on every key-value pair. Let's see how we can implement such a function − ExampleforEach(callback) {    for (let prop in this.container) {       // Call the callback as: callback(key, value)       callback(prop, this.container[prop]);    } }You can test this using − Exampleconst myMap = new MyMap(); myMap.put("key1", "value1"); myMap.put("key2", "value2"); myMap.forEach((k, v) => console.log(`Key is ${k} and value is ${v}`));OutputThis will give the output −Key is key1 and value is value1 Key is key2 and value is value2ES6 ... Read More

We'll implement a clear() function that simply clears the contents of the container. For example,  Exampleclear() {    this.container = {} }You can test this using − Exampleconst myMap = new MyMap(); myMap.put("key1", "value1"); myMap.put("key2", "value2");   myMap.display(); myMap.clear(); myMap.display();OutputThis will give the output −{ key1: 'value1', key2: 'value2' }You can use the clear method in the same way in ES6 maps as well. For example, Exampleconst myMap = new Map([    ["key1", "value1"],    ["key2", "value2"] ]); console.log(myMap) myMap.clear(); console.log(myMap)OutputThis will give the output −Map { 'key1' => 'value1', 'key2' => 'value2' } Map {}Read More

Sometimes when working with a dictionary, we need only the keys of the dictionary as an array for some task. We can easily get the properties of an object using Object.keys. We'll use this method to return the keys from our container object. Examplekeys() {    return Object.keys(this.container); }You can test this using − Exampleconst myMap = new MyMap(); myMap.put("key1", "value1"); myMap.put("key2", "value2"); console.log(myMap.keys());OutputThis will give the output −[ 'key1', 'key2' ]In ES6 Map, the same method is available that you can use. Note that it returns a MapIterator object, which you can convert to an array or use like a ... Read More

We'll implement the get method that searches a given key in the dictionary. Exampleget(key) {    if(this.hasKey(key)) {       return this.container[key];    }    return undefined; }Again, JS objects are very much implemented like dictionaries, hence have most of the functionality we can use directly without any more code needed. This is also heavily optimized, so you don't have to worry about the runtime of the function.You can test this using − Exampleconst myMap = new MyMap(); myMap.put("key1", "value1"); myMap.put("key2", "value2"); console.log(myMap.get("key1")) console.log(myMap.get("key2")) console.log(myMap.get("key3"))OutputThis will give the output −value1 value2 undefinedIn ES6, you have the same functionality using the ... Read More

To remove an element from the dictionary, we first need to check if it exists in the dictionary.We'll use the hasKey method for that. Then we can directly delete it using the delete operator.We'll return a Boolean so that the place where we call this method can know whether the key already existed or not in the dictionary. Exampledelete(key) {    if(this.hasKey(key)) {       delete this.container[key];       return true;    }    return false; }You can test this using − Exampleconst myMap = new MyMap(); myMap.put("key1", "value1"); myMap.put("key2", "value2"); myMap.display(); myMap.delete("key2"); myMap.display();OutputThis will give the output ... Read More

Now we'll create the put method that'll allow us to put key-value pairs on the dictionary. Now using this we'll implement the put method.Note that JS has objects that act quite like dictionaries. We can just set the container's key property to value. Exampleput(key, value) {    this.container[key] = value; }You can test this and the previous functions using − Exampleconst myMap = new MyMap() myMap.put("key1", "value1") myMap.put("key2", "value2") myMap.display() console.log(myMap.hasKey("key1")); console.log(myMap.hasKey("key3"));OutputThis will give the output −{key1: "value1", key2: "value2"} true falseIn ES6, you can put a key-value pair in a map using the set method. For example,  Exampleconst myMap ... Read More

Let's create a MyMap class so that it doesn't hide the actual Map class in JS. We'll create a container object that'll keep track of all our values that we add to the map. We'll also create a display function that prints the map for us. Exampleclass MyMap {    constructor() {       this.container = {};    }    display() {       console.log(this.container);    } }In ES6, you can directly create a dictionary using the Map class. For example,  Exampleconst map1 = new Map(); const map2 = new Map([    ["key1", "value1"],    ["key2", "value2"] ]);Checking if ... Read More