Crack JavaScript Job Interview, Web Developer Job | Tech21k

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What is Javascript ?

JavaScript is a programming language initially designed to interact with elements of web pages. In web browsers. 

JavaScript allows you to add interactivity to a web page. Typically, you use JavaScript with HTML and CSS to enhance a web page’s functionality, such as validating forms, creating interactive maps, and displaying animated charts.

JavaScript History

In 1995, JavaScript was created by a Netscape developer named Brendan Eich. First, its name was Mocha. And then, its name was changed to LiveScript.

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Javascript Interviews Questions answer

The vast majority of the significant subjects have been covered that is nearly asked in every one of the meetings, so set up this multitude of ideas well. Good luck for you Meetings

Q. 1. What are closures? Advantage and Disadvantage

Conclusion is a mix of capabilities packaged together in a lexical extension. The inward capability approaches an external capability degree, factors and boundaries even after the external capability has returned.

Advantages of closures: 1.

1. Callbacks implementation in javascript is heavily dependent on how closures work

2. Mostly used in Encapsulation of the code

3. Also used in creating API calling wrapper methods

Disadvantages of closures:

1. Variables used by closure will not be garbage collected

2. Memory snapshot of the application will be increased if closures are not used properly

Q. 2. Difference between regular function vs arrow function?

1. Syntax – No implicit return for arrow function
2. Argument Binding – In regular function, Arguments keywords can be used to access the arguments of which passed to function.

3. this keyword – Normal function depends on how it is being called and arrow function is on where it is being called.

4. New keyword – Regular functions are constructible, they can be called using the new keyword

5. Function Hoisting – In regular function, function gets hoisting at top.

Q. 3. What is Lexical Environment / lexical Scope?

Lexical perusing implies that the availability of not set in stone by the place of the factors inside the settled extensions.

Simpler, the lexical scoping means that inside the inner scope you can access variables of outer scopes.

It’s called lexical (or static) on the grounds that the motor decides (at lexing time) the settling of extensions by simply taking a gander at the JavaScript source code, without executing it.