Software Style Guide

Most of the style guide recommendations here come from Douglas Crockford’s book JavaScript, the good parts

Tabs or spaces?

We always indent 4 spaces.

Underscores or camelCase?

We use camelCase for function names and underscores for variables names.

For example:

function thisIsAFunction () {
    let this_is_a_variable;
    ...
}

const versus let

Try to use const whenever possible. If a variable won’t be reassigned, use const, otherwise use let.

Spaces around operators

In general, spaces are put around operators, such as the equals = or plus + signs.

For example:

if (sublocale != locale) {
    // do something
}

An exception is when they appear inside for-loop expressions, for example:

for (i=0; i<msgs_length; i++) {
    // do something
}

Generally though, rather err on the side of adding spaces, since they make the code much more readable.

destructuring

When assigning to a variable via destructuring, add spaces between the curly brackets.

For example:

const { foo } = bar;

Global constants are written in ALL_CAPS

Global identifiers that denote constant values should be written in all capital letters, with underscores between words.

For example:

const SECONDS_IN_HOUR = 3600;

function update () {
    const timeout = 20;
    let seconds_since_message = 0;
    // other stuff here
}

Function declaration and invocation

When declaring a function, the function name and the brackets after it are separated with a space. Like so:

function update (model) {
    model.foo = 'bar';
}

When calling the same function, the brackets are written without a space in between:

update(model);

This is to make a more explicit visual distinction between method declarations and method invocations.

Checking for equality

JavaScript has a strict === and less strict == equality operator. The stricter equality operator also does type checking. To avoid subtle bugs when doing comparisons, always use the strict equality check.

Curly brackets

Curly brackets must appear on the same lines as the if and else keywords. The closing curly bracket appears on its own line.

For example:

if (locales[locale]) {
    return locales[locale];
} else {
    sublocale = locale.split("-")[0];
    if (sublocale != locale && locales[sublocale]) {
        return locales[sublocale];
    }
}

Always enclose blocks in curly brackets

When writing a block such as an if or while statement, always use curly brackets around that block of code. Even when not strictly required by the compiler (for example if its only one line inside the if statement).

For example, like this:

if (condition === true) {
    this.updateRoomsList();
}
somethingElse();

and NOT like this:

if (converse.auto_list_rooms)
    this.updateRoomsList();
somethingElse();

This is to aid in readability and to avoid subtle bugs where certain lines are wrongly assumed to be executed within a block.