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.
Indeed, What is array in JavaScript?
Arrays are a special type of objects. The typeof operator in JavaScript returns “object” for arrays. But, JavaScript arrays are best described as arrays. Arrays use numbers to access its “elements”.
Then, What are promises in JavaScript? A Promise is a JavaScript object that links producing code and consuming code.
What is Arrow function in JavaScript? 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; }
In the same way 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.
What are the datatypes in JavaScript?
JavaScript types
- Boolean type.
- Null type.
- Undefined type.
- Number type.
- BigInt type.
- String type.
- Symbol type.
What is DOM in JavaScript?
The Document Object Model (DOM) is the data representation of the objects that comprise the structure and content of a document on the web.
What is let in JavaScript?
let allows you to declare variables that are limited to the scope of a block statement, or expression on which it is used, unlike the var keyword, which declares a variable globally, or locally to an entire function regardless of block scope.
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 is callback in JS?
A JavaScript callback is a function which is to be executed after another function has finished execution. A more formal definition would be – Any function that is passed as an argument to another function so that it can be executed in that other function is called as a callback function.
What is callback in node JS?
Callback is an asynchronous equivalent for a function. A callback function is called at the completion of a given task. Node makes heavy use of callbacks. All the APIs of Node are written in such a way that they support callbacks.
What does the ++ mean in JavaScript?
The increment operator ( ++ ) increments (adds one to) its operand and returns a value.
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.
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 throttling in JavaScript?
Throttling or sometimes is also called throttle function is a practice used in websites. Throttling is used to call a function after every millisecond or a particular interval of time only the first click is executed immediately.
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 null in JS?
The value null represents the intentional absence of any object value. It is one of JavaScript’s primitive values and is treated as falsy for boolean operations.
What is == and === in JavaScript?
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What is primitive in JavaScript?
In JavaScript, a primitive (primitive value, primitive data type) is data that is not an object and has no methods. There are 7 primitive data types: string, number, bigint, boolean, undefined, symbol, and null.
What is document in JavaScript?
JavaScript Document object is an object that provides access to all HTML elements of a document. When an HTML document is loaded into a browser window, then it becomes a document object. The document object stores the elements of an HTML document, such as HTML, HEAD, BODY, and other HTML tags as objects.
What are attributes in JavaScript?
attributes : a collection of objects that belong to a built-in Attr class, with name and value properties.
What are objects in JavaScript?
In JavaScript, an object is a standalone entity, with properties and type. Compare it with a cup, for example. A cup is an object, with properties. A cup has a color, a design, weight, a material it is made of, etc. The same way, JavaScript objects can have properties, which define their characteristics.
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