File Metrics for JavaScript

This document outlines the definition of file metrics for JavaScript.

complexity

The "complexity" metric counts:

if and else if statements
ternary expressions and nullish coalescing operators
for...of, for await...of, for...in,while and do...while loops
case labels in switch-statements
catch blocks
logical binary operations && and ||
everything counted for the "functions" metric

It does not count:

.catch() method call for Promises
.forEach() method call for iterables and other built-in functions

functions

The "functions" metric counts:

static initialization blocks
function declarations and expressions with function,function*, async function and async function*
constructors, getter (get <method_name>), setter (set <method_name>), and methods of classes and objects
arrow functions

It does not count:

functions created from the constructors new Function(), new GeneratorFunction(), new AsyncFunction() and new AsyncGeneratorFunction(). Ex:
```
const generator = new GeneratorFunction("a", "yield a * 2"); //we don't count this as function
const iterator = generator(10);
```

classes

The "classes" metric counts:

class definitions

lines_of_code, comment_lines, real_lines_of_code and keywords_in_comments