wip: add more questions

src/data/question-groups/javascript/content/defer-vs-async.md

@@ -0,0 +1,25 @@
+The main difference between `defer` and `async` is the order of execution.
+
+## Defer attribute
+
+A `<script>` element with a `defer` attribute, it will continue to load the HTML page and render it while the script is being downloaded. The script is executed after the HTML page has been completely parsed. `defer` scripts maintain their order in the document.
+
+```html
+<script defer src="script1.js"></script>
+<script defer src="script2.js"></script>
+```
+
+In the example above, `script1.js` will be executed before `script2.js`. The browser will download both scripts in parallel, but `script1.js` will be executed after the HTML page has been parsed and `script2.js` will be executed after `script1.js` has been executed.
+
+## Async attribute
+
+On the other hand, A `<script>` element with an `async` attribute, it will pause the HTML parser and execute the script immediately after it has been downloaded. The HTML parsing will resume after the script has been executed.
+
+```html
+<script async src="script1.js"></script>
+<script async src="script2.js"></script>
+```
+
+In the example above, the browser will download both scripts in parallel, and execute them as soon as they are downloaded. The order of execution is not guaranteed.
+
+To know more you can check [this diagram](https://roadmap.sh/guides/avoid-render-blocking-javascript-with-async-defer) from us that explains the difference between `defer` and `async` in a visual way.

src/data/question-groups/javascript/content/increment-operator.md

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+As the name says, the increment operator increases the value of a variable by **1**. There are two types of increment operators: `pre-increment` and `post-increment`.
+
+## Pre-increment
+
+The pre-increment operator increases the value of a variable by 1 and then returns the value. For example:
+
+```js
+let x = 1;
+console.log(++x); // 2
+console.log(x); // 2
+```
+
+## Post-increment
+
+The post-increment operator returns the value of a variable and then increases the value by 1. For example:
+
+```js
+let x = 1;
+console.log(x++); // 1
+console.log(x); // 2
+```

src/data/question-groups/javascript/javascript.md

@@ -236,4 +236,14 @@ questions:
     topics:
       - 'Core'
       - 'Intermediate'
+  - question: Difference between `defer` and `async` attributes in JavaScript?
+    answer: defer-vs-async.md
+    topics:
+      - 'Core'
+      - 'Beginner'
+  - question: What is Increment operator in JavaScript?
+    answer: increment-operator.md
+    topics:
+      - 'Core'
+      - 'Beginner'
 ---