Control Structures

Conditional Statements

As mentioned, Javascript's syntax is similar to Java's, especially their control structures.

// If statement 
var count = 1;
if (count == 3){
    // evaluated if count is 3
} else if (count == 4){
    // evaluated if count is 4
} else {
    // evaluated if it's none of the above
}

// switch statement
// checks for equality with ===
// use break after each case or the cases after the correct one will be executed too. 
grade = 'B';
switch (grade) {
  case 'A':
    console.log("Great job");
    break;
  case 'B':
    console.log("OK job");
    break;
  case 'C':
    console.log("You can do better");
    break;
  default:
    console.log("Oy vey");
    break;
}

This prints to console:

OK job

Loops

// While(condition) statement
while (true){
    // An infinite loop. Don't do this!
}

// Do-while loops are like while loops, except they always run at least once.
// Here's an example usage:
var input;
do {
    input = getInput();
} while (!isValid(input))

// Javascript has a messy for-each loop situation, so for now, you can just use for loops: 

// For loops
// initialization; continue condition; iteration.
for (var i = 0; i < 5; i++){
    console.log("Number " + i);
}

The for loop will print to the console:

Number 0
Number 1
Number 2
Number 3
Number 4