Relawan kami belum menerjemahkan artikel ini ke bahasa Bahasa Indonesia. Bergabunglah dan bantu kami menyelesaikannya!
Anda juga dapat membaca artikel ini dalam English (US).
The if
statement executes a statement if a specified condition is truthy. If the condition is falsy, another statement can be executed.
Syntax
if (condition) statement1 [else statement2]
- condition
- An expression that is considered to be either truthy or falsy.
- statement1
- Statement that is executed if condition is truthy. Can be any statement, including further nested
if
statements. To execute multiple statements, use a block statement ({ ... }) to group those statements. To execute no statements, use an empty statement.
- statement2
- Statement that is executed if condition is falsy and the
else
clause exists. Can be any statement, including block statements and further nestedif
statements.
Description
Multiple if...else
statements can be nested to create an else if
clause. Note that there is no elseif
(in one word) keyword in JavaScript.
if (condition1) statement1 else if (condition2) statement2 else if (condition3) statement3 ... else statementN
To see how this works, this is how it would look if the nesting were properly indented:
if (condition1) statement1 else if (condition2) statement2 else if (condition3) ...
To execute multiple statements within a clause, use a block statement ({ ... }
) to group those statements. In general, it is a good practice to always use block statements, especially in code involving nested if
statements:
if (condition) { statements1 } else { statements2 }
Do not confuse the primitive Boolean values true
and false
with truthiness or falsiness of the Boolean
object. Any value that is not false
, undefined
, null
, 0
, -0
, NaN
, or the empty string (""
), and any object, including a Boolean object whose value is false, is considered truthy when used as the condition. For example:
var b = new Boolean(false); if (b) // this condition is truthy
Examples
Using if...else
if (cipher_char === from_char) { result = result + to_char; x++; } else { result = result + clear_char; }
Using else if
Note that there is no elseif
syntax in JavaScript. However, you can write it with a space between else
and if
:
if (x > 5) { /* do the right thing */ } else if (x > 50) { /* do the right thing */ } else { /* do the right thing */ }
Assignment within the conditional expression
It is advisable to not use simple assignments in a conditional expression, because the assignment can be confused with equality when glancing over the code. For example, do not use the following code:
if (x = y) { /* do the right thing */ }
If you need to use an assignment in a conditional expression, a common practice is to put additional parentheses around the assignment. For example:
if ((x = y)) { /* do the right thing */ }
Specifications
Browser compatibility
Desktop | Mobile | Server | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Basic support | Chrome Full support Yes | Edge Full support Yes | Firefox Full support 1 | IE Full support Yes | Opera Full support Yes | Safari Full support Yes | WebView Android Full support Yes | Chrome Android Full support Yes | Edge Mobile Full support Yes | Firefox Android Full support 4 | Opera Android Full support Yes | Safari iOS Full support Yes | Samsung Internet Android Full support Yes | nodejs Full support Yes |
Legend
- Full support
- Full support