Asked by: Celino Pe├žas
technology and computing web development

Is JavaScript blocking or nonblocking?

Last Updated: 29th June, 2020

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Blocking. Blocking is when the execution of additional JavaScript in the Node. js process must wait until a non-JavaScript operation completes. This happens because the event loop is unable to continue running JavaScript while a blocking operation is occurring.

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Simply so, why JavaScript is non blocking?

JavaScript engine is single threaded so the language itself is synchronous and hence blocking in nature. However, a feature called “event loop” is provided by the environment where javascript is running which provides capability for asynchronous execution providing non-blocking functionality.

Additionally, why is JavaScript asynchronous? JavaScript is always synchronous and single-threaded. JavaScript is only asynchronous in the sense that it can make, for example, Ajax calls. The Ajax call will stop executing and other code will be able to execute until the call returns (successfully or otherwise), at which point the callback will run synchronously.

Subsequently, question is, is JavaScript asynchronous by default?

How to deal with asynchronous code in JavaScript. JavaScript is synchronous by default and is single threaded. This means that code cannot create new threads and it will execute your code block by order after hoisting.

Why is JavaScript single threaded?

Javascript is a single threaded language. This means it has one call stack and one memory heap. As expected, it executes code in order and must finish executing a piece code before moving onto the next. Once those tasks are finished by the browser, they return and are pushed onto the stack as a callback.

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