Web BuildingLesson 64Free preview

Web JavaScript

This lesson is part of W3.CSS · All levels

Summary

JavaScript makes the page interactive: it responds to clicks, validates content, and updates the view without reloading. You work with variables, functions, and DOMs selected through querySelector. The code runs on the user side, so always make sure the results stay logical even if JavaScript is turned off.

Key points

Use const when the value does not change and let for frequently changing values
Event listener handles actions such as clicks and inputs
QuerySelector selects the first element that matches
The array functions and methods help to process the data
Check the browser console for errors

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