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uni/year2/semester1/logseq-stuff/pages/JavaScript Functions & Events.md

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- #[[CT216 - Software Engineering I]]
- **Previous Topic:** [[Bootstrap CSS]]
- **Next Topic:** [[Introduction to NodeJS]]
- **Relevant Slides:** ![Week 8 - JavaScript - Functions, Events.pdf](../assets/Week_8_-_JavaScript_-_Functions,_Events_1668007671511_0.pdf)
-
- # Functions
collapsed:: true
- A function can be named or it can be anonymous.
- ## ES6 Arrow Functions
- Arrow functions are more concise - a developer can achieve the same functionality with fewer lines of code.
- ```javascript
// ES6 Arrow Function
(param1, param2) =>
{
return param1 * param2;
}
// ES5 Traditional Function
function(param1, param2)
{
return param1 * param2;
}
```
- ## Assigning a Function to a Variable
- ```javascript
let multiply = (param1, param2) => {
return param1 * param2;
}
multiply(2,3)
```
- # Events
- An **event** is an action that can be responded to by JavaScript.
- Every element on a page has certain events which can trigger some code.
- We can identify when a user clicks a button with the `onClick` event.
- ## Event Examples
- ### Mouse Events
- `onClick`: Triggered when the mouse clicks on an element.
- `onMouseDown`: Triggered when the mouse button is pressed.
- `onMouseUp`: Triggered when the mouse button is released.
- `onMouseOver`: Triggered for an element when the mouse cursor is moved over that element.
- `onMouseOut`: Triggered for an element when the mouse cursor is moved away from that element.
- ### Selecting & De-Selecting Elements
- `onFocus`: Triggered when an element gets focus.
- `onBlur`: Triggered when an element loses focus.
- `onChange`: Triggered when the content of an element changes.
- ### Keyboard Events
- `onKeyDown`: Triggered when a keyboard key is pressed.
- `onKeyUp`: Triggered when a keyboard key is released.
- `onKeyPress`: Triggered when a keyboard key is pressed or held.
- `onSelect`: Triggered when text is selected.
-