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JavaScript

1 year ago
// console.log("Hello World");
// [Section] While Loop
/*
- A while loop takes in an expression/condition
- Expressions are any unit of code that can be evaluated to a value
- If the condition evaluates to true, the statements inside the code block will be executed
- A statement is a command that the programmer gives to the computer
- A loop will iterate a certain number of times until an expression/condition is met
- "Iteration" is the term given to the repetition of statements
- Syntax
while(expression/condition) {
statement
}
*/
let count = 5;
// While the value of count is not equal to 0
while(count !== 0) {
// The current value of count is printed out
console.log("While: " + count);
// Decreases the value of count by 1 after every iteration to stop the loop when it reaches 0
// Loops occupy a significant amount of memory space in our devices
// Make sure that expressions/conditions in loops have their corresponding increment/decrement operators to stop the loop
// Forgetting to include this in loops will make our applications run an infinite loop which will eventually crash our devices
// After running the script, if a slow response from the browser is experienced or an infinite loop is seen in the console quickly close the application/browser/tab to avoid this
count--;
}
// [Section] Do While Loop
/*
- A do-while loop works a lot like the while loop. But unlike while loops, do-while loops guarantee that the code will be executed at least once.
- Syntax
do {
statement
} while (expression/condition)
*/
/*
- The "Number" function works similarly to the "parseInt" function
- Both differ significantly in terms of the processes they undertake in converting information into a number data type and other features that help with manipulating data
- The "prompt" function creates a pop-up message in the browser that can be used to gather user input
- How the Do While Loop works:
1. The statements in the "do" block executes once
2. The message "Do While: " + number will be printed out in the console
3. After executing once, the while statement will evaluate whether to run the next iteration of the loop based on given expression/condition (e.g. number less than 10)
4. If the expression/condition is not true, another iteration of the loop will be executed and will be repeated until the condition is met
5. If the expression/condition is true, the loop will stop
*/
// let number = Number(prompt("Give me a number"));
// do {
// // The current value of number is printed out
// console.log("Do While: " + number);
// // Increases the value of number by 1 after every iteration to stop the loop when it reaches 10 or greater
// // number = number + 1
// number += 1;
// // Providing a number of 10 or greater will run the code block once and will stop the loop
// } while (number < 10)
// [Section] For Loop
/*
- A for loop is more flexible than while and do-while loops. It consists of three parts:
1. The "initialization" value that will track the progression of the loop.
2. The "expression/condition" that will be evaluated which will determine whether the loop will run one more time.
3. The "finalExpression" indicates how to advance the loop.
- Syntax
for (initialization; expression/condition; finalExpression) {
statement
}
*/
/*
- Will create a loop that will start from 0 and end at 20
- Every iteration of the loop, the value of count will be checked if it is equal or less than 20
- If the value of count is less than or equal to 20 the statement inside of the loop will execute
- The value of count will be incremented by one for each iteration
*/
for (let count = 0; count <= 20; count++) {
// The current value of count is printed out
console.log(count);
}
// for (let count = 0; count >= -20; count--) {
// console.log(count);
// }
let myString = "alex";
console.log(myString.length);
// Accessing index number
console.log(myString[0]);
console.log(myString[1]);
console.log(myString[2]);
for(let x = 0; x < myString.length; x++) {
console.log(myString[x])
}
let myName = "AlEx";
for (let i=0; i < myName.length; i++) {
if (
myName[i].toLowerCase() == "a" ||
myName[i].toLowerCase() == "i" ||
myName[i].toLowerCase() == "u" ||
myName[i].toLowerCase() == "e" ||
myName[i].toLowerCase() == "o"
){
// If the letter in the name is a vowel, it will print the number 3
console.log(3);
} else {
// Print in the console all non-vowel characters in the name
console.log(myName[i])
}
}
// [SECTION] Continue and Break statements
for (let count = 0; count <= 20; count++) {
// if remainder is equal to 0
if (count % 2 === 0) {
// Tells the code to continue to the next iteration of the loop
// This ignores all statements located after the continue statement;
continue;
}
// The current value of number is printed out if the remainder is not equal to 0
console.log("Continue and Break: " + count);
// If the current value of count is greater than 10
if (count > 10) {
// Tells the code to terminate/stop the loop even if the expression/condition of the loop defines that it should execue so long as the value of count is less than or equal to 20
// number values after 10 will no longer be printed
break;
}
}
let name = "alexandro";
for (let i = 0; i < name.length; i++) {
console.log(name[i]);
if (name[i].toLowerCase() === "a") {
console.log("Continue to the next iteration");
continue;
}
if (name[i] == "d") {
break;
}
}