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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
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 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
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
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
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
A set is an abstract data type that can store certain values, without any particular order and no repeated values. It is a computer implementation of the mathematical concept of a finite set. Unlike most other collection types, rather than retrieving a specific element from a set, one typically tests a value for membership in a set.
Whenever you want to store unique elements in a container for which the order doesn't matter and you mainly want to use it to check for membership of different objects.Sets are also useful when you want to perform operations like union, intersection, a difference like you do in mathematical sets.Let's look at both how we can define our own set and use the existing one in ES6.Methods we'll implementThe ES6 set API provides some methods. We'll implement these methods in our implementation and also look at how to use them using the built-in class.add() − Adds a new element to the ... Read More
Let's create a MySet class so that it doesn't hide the actual set class in JS. We'll create a container object that'll keep track of all our values that we add to the set. We'll also create a display function that prints the set for us. Exampleclass MySet { constructor() { this.container = {}; } display() { console.log(this.container); } }In ES6, you can directly create a set using the Set class. For example, Exampleconst set1 = new Set(); const set2 = new Set([1, 2, 5, 6]);Checking for membershipThe has method checks ... Read More
The delete method checks if a value already exists in the set, if it does, then it removes that value from the set. We can implement it as follows &minusl Exampledelete(val) { if (this.has(val)) { delete this.container[val]; return true; } return false; }You can test this using − Exampleconst testSet = new MySet(); testSet.add(1); testSet.add(2); testSet.add(5); testSet.delete(5); testSet.delete(2); testSet.display(); console.log(testSet.has(5)); console.log(testSet.has(20)); console.log(testSet.has(1));OutputThis will give the output −{ '1': 1} False False TrueIn ES6, you use the delete function as follows − Exampleconst testSet = new MySet(); testSet.add(1); testSet.add(2); testSet.add(5); testSet.delete(5); ... Read More