ConditionalStatements.md

Conditional statements

A conditional statement is a set of commands that executes if a specified condition is true. JavaScript supports two conditional statements: if...else and switch.

if-else statements

Use the if statement to execute a statement if a logical condition is true. Use the optional else clause to execute a statement if the condition is false

if (condition) { statement_1; } else { statement_2; }

Here the condition can be any expression that evaluates to true or false

Falsy values

• false
• undefined
• 0
• null
• NaN
• the empty string("")

All other values, including all objects, evaluate to true when passed to a conditional statement.

Do not confuse the primitive boolean values true and false with the true and false values of the Boolean object. For example:

    var b = new Boolean(false);
    if (b) // this condition evaluates to true
    if (b == true) // this condition evaluates to false

switch statement

A switch statement allows a program to evaluate an expression and attempt to match the expression's value to a case label. If a match is found, the program executes the associated statement.

switch(expression) {
    case label_1:
        statement_1:
        [break;]
    case label_2:
        statement_2:
        [break;]
        ...
    default:
    statements_def
    [break;]
}