Javascript-Coding Style

Javascript-Coding Style

Coding conventions secure quality:

• Improves code readability
• Make code maintenance easier

Syntax:

Variable Names:

You use camelCase for identifier names variables and functions.

All names start with a letter.

Syntax:

firstName = "I2tutorials";
lastName = "javascript";

price = 19.90;
tax = 0.20;

fullPrice = price + (price * tax);

Spaces Around Operators:

Always put spaces around operators ( = + – * / ), and after commas:

Syntax:

var x = y + z;
var values = ["java", "css", "html"];

Code Indentation:

Always use two spaces for indentation of code blocks:

Syntax:

function toCelsius(fahrenheit) {
 return (5 / 9) * (fahrenheit - 32);
}

Statement Rules:

Always end a simple statement with a semicolon.

Syntax:

var values = ["html", "css", "javascript"];

var person = {
 firstName: "I2",
 lastName: "Tutorials",
 age: 50,
 eyeColor: "green"
};

General rules for complex or compound statements:

• Place the opening brackets at the end of the first line.
• Use one space before the opening brackets.
• Place the closing brackets on a new line, without leading spaces.
• Do not end a complex or compound statement with a semicolon.

Functions:

function toCelsius(fahrenheit) {
 return (5 / 9) * (fahrenheit - 32);
}

Loops:

for (i = 0; i < 5; i++) {
 x += i;
}

Conditionals:

if (time < 20) {
  greeting = "Good day";
} else {
  greeting = "Good evening";
}

Object Rules:

• Place the opening brackets on the same line as the object name.
• Use colon plus (: +)one space between each property and its value.
• Use quotes (” “,’ ‘)around string values, not around numeric values.
• Do not add a comma(,) after the last property-value pair.
• Place the closing brackets on a new line, without leading spaces.
• Always end an object definition with a semicolon(;).

Example

var person = {
 firstName: "I2",
 lastName: "Tutorials",
 age: 50,
 eyeColor: "green"
};

Naming Conventions:

• Variable and function names are written as camelCase.
• Global variables are written in UPPERCASE (We don’t, but it’s quite common).
• Constants (like PI) written in UPPERCASE.