JavaScript Conditionals Part 1
An introduction to JavaScript conditional statements
Conditional Statements Part 1
Conditional statements are used to direct the flow of the program.
if statements
These are often used to branch conditions. This example outputs through HTML using docuemtn.
%%html
<output id="output"></output>
<script>
function intializeData(data = null) {
// Define default values
let scaleFactor = 9/16;
let animationRate = 1;
let position = [0, 0];
// Check if data is provided
if (data) {
scaleFactor = data.SCALE_FACTOR || scaleFactor;
animationRate = data.ANIMATION_RATE || animationRate;
position = data.INIT_POSITION || position;
}
document.getElementById("output").innerHTML = `
<p>Scale Factor: ${scaleFactor}</p>
<p>Animation Rate: ${animationRate}</p>
<p>Initial Position: ${position}</p>
`;
}
var data = {
SCALE_FACTOR: 1/1,
ANIMATION_RATE: 25,
INIT_POSITION: [100, 100]
}
// Uncomment one of the following lines to test the if statement in the function
//intializeData();
intializeData(data);
</script>
switch case statement
These are often used to branch code when there are a lot of options.
%%javascript
class GameObject {
constructor() {
this.velocity = { x: 0, y: 0 };
this.direction = '';
this.xVelocity = 1;
this.yVelocity = 1;
}
handleKeyDown({ keyCode }) {
switch (keyCode) {
case 87: // 'W' key
this.direction = 'up';
break;
case 65: // 'A' key
this.direction = 'left';
break;
case 83: // 'S' key
this.direction = 'down';
break;
case 68: // 'D' key
this.direction = 'right';
break;
}
}
}
// Example usage
const gameObject = new GameObject();
console.log('Initial State:', gameObject);
gameObject.handleKeyDown({ keyCode: 87 }); // Simulate 'W' key press
console.log('After W Key Press:', gameObject);
gameObject.handleKeyDown({ keyCode: 65 }); // Simulate 'A' key press
console.log('After A Key Press:', gameObject);
gameObject.handleKeyDown({ keyCode: 83 }); // Simulate 'S' key press
console.log('After S Key Press:', gameObject);
gameObject.handleKeyDown({ keyCode: 68 }); // Simulate 'D' key press
console.log('After D Key Press:', gameObject);
<IPython.core.display.Javascript object>