Intermediate Javascript

[altabz]

I’m confuse I am studying Learn Intermediate Javascript right now. The lesson is Request fetch API. The lesson is using terms such us document.querySelector and JSON. I have no idea how this things work. Should I stop the intermediate course and learn first this JSON, query Selector and event listener?

[javaace96747]

If you haven’t already learned these things and the objective of the course isn’t to teach you these things, then I would definitely learn those things first.

To summarize though, document.querySelector() is a method on the document object. The document object comes from the Document Object Model (the DOM) which is a way of rendering and visualizing webpages. The querySelector() method searches the document object, which is the object at the top of the tree of all elements on a webpage, and returns the first object/element which has the CSS selector provided as its argument. As an example,

// JS:
const firstDiv = document.querySelector('first-div')

// HTML
<div class='first-div'>Hello world</div>

allows me to select that div and tie it to a variable. Then, I can manipulate it.

JSON is Javascript Object Notation and it is a way of serializing (translating) information between applications and parts of applications. It’s built on similar syntax to Javascript objects, hence the name.

{
    greeting: {
        message: "Hi, I'm a JSON object property.",
        author: "Me!"
    }
}

That’s a valid JSON file with a single object with various properties.

[altabz]

Is the DOM course part of CSS? and how about JSON which course I need to take to learn this topic?

[javaace96747]

DOM and JSON are both somewhere in the Javascript courses.