Arrow function is one of the features introduced in the ES6 version of JavaScript. It allows you to create functions in a cleaner way compared to regular functions. For example, This function // function expression let x = function(x, y) { return x * y; }
Indeed, What is curry in JavaScript?
In other terms, currying is when a function — instead of taking all arguments at one time — takes the first one and returns a new function, which takes the second one and returns a new function, which takes the third one, etc. until all arguments are completed.
Then, What are promises in JavaScript? A Promise is a JavaScript object that links producing code and consuming code.
What are prototypes in JavaScript? Prototypes are the mechanism by which JavaScript objects inherit features from one another. In this article, we explain what a prototype is, how prototype chains work, and how a prototype for an object can be set.
In the same way What is map in JavaScript? Definition and Usage. map() creates a new array from calling a function for every array element. map() calls a function once for each element in an array. map() does not execute the function for empty elements.
What is JavaScript closure?
A closure is the combination of a function bundled together (enclosed) with references to its surrounding state (the lexical environment). In other words, a closure gives you access to an outer function’s scope from an inner function.
What are generators in JavaScript?
A generator is a process that can be paused and resumed and can yield multiple values. A generator in JavaScript consists of a generator function, which returns an iterable Generator object.
What is pure function in JavaScript?
A Pure Function has all the above characteristics. It is a function that produces the same output for the same input. It means it returns the same result when you pass the same arguments. A pure function shouldn’t have any side effects to change the expected output.
What is async and await in JavaScript?
1. The word “async” before a function means one simple thing: a function always returns a promise. 2. The keyword “await” makes JavaScript wait until that promise settles and returns its result.
What makes JavaScript asynchronous?
Asynchronous programming is a technique that enables your program to start a potentially long-running task, and then rather than having to wait until that task has finished, to be able to continue to be responsive to other events while the task runs.
What are closures in JavaScript?
A closure is the combination of a function bundled together (enclosed) with references to its surrounding state (the lexical environment). In other words, a closure gives you access to an outer function’s scope from an inner function.
What is constructor function in JavaScript?
A constructor is a special function that creates and initializes an object instance of a class. In JavaScript, a constructor gets called when an object is created using the new keyword. The purpose of a constructor is to create a new object and set values for any existing object properties.
Why prototype is used in JavaScript?
A prototype is an existing inbuilt functionality in JavaScript. Whenever we create a JavaScript function, JavaScript adds a prototype property to that function. A prototype is an object, where it can add new variables and methods to the existing object.
Is JavaScript map asynchronous?
The . map() algorithm applies an async callback to each element of an array, creating promises as it does. However, the returned result by . map() is no promise, but an array of promises.
What is key value pair in JavaScript?
A property is a “key: value” pair, where key is a string (also called a “property name”), and value can be anything. We can imagine an object as a cabinet with signed files. Every piece of data is stored in its file by the key.
How do you hash in JavaScript?
You can implement a Hash Table in JavaScript in three steps:
- Create a HashTable class with table and size initial properties.
- Add a hash() function to transform keys into indices.
- Add the set() and get() methods for adding and retrieving key/value pairs from the table.
What is == and === in JavaScript?
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What is the type of null in JavaScript?
In JavaScript null is “nothing”. It is supposed to be something that doesn’t exist. Unfortunately, in JavaScript, the data type of null is an object. You can consider it a bug in JavaScript that typeof null is an object.
What is yield in JavaScript?
The yield keyword pauses generator function execution and the value of the expression following the yield keyword is returned to the generator’s caller. It can be thought of as a generator-based version of the return keyword. yield can only be called directly from the generator function that contains it.
What is promise in JavaScript?
The Promise object represents the eventual completion (or failure) of an asynchronous operation and its resulting value.
What is mutation in JavaScript?
Mutations. A value is said to be mutable if it can be changed. That’s all there is to it: a mutation is the act of changing the properties of a value. All primitive value in JavaScript are immutable: you can’t change their properties — ever.
What is immutability in JavaScript?
Immutables are the objects whose state cannot be changed once the object is created. Strings and Numbers are Immutable.
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