chain-methods

Chain Methods

This module exposes a single function to transform a plain object into a class, where methods can be chained.

Installation

npm install chain-methods

Usage

const chainMethods = require('chain-methods');
const Path = chainMethods(require('path'));

const rootPath = new Path(__dirname);
const imagesPath = rootPath.join('dist/static/images');

// With `chainMethods`:
const stream = fs.createReadStream(imagesPath.join('foo.jpg').value);

Why

This module was created for experimentation purposes. It works well for APIs like node's path and url modules, where the first argument of each function is consistent.

It makes code a little easier to read by avoiding this type of nesting:

const foo = obj.method1(obj.method2('bar'), 'baz');

Limitations

The first argument of each method must be consistent.

const Calculator = chainMethods({
    // Good:
    add: (n1, n2) => n1 + n2,
    subtract: (n1, n2) => n1 - n2,
    
    // Bad:
    operation(operationName, ...args) {
        return this[operationName](...args);
    },
});
const value = new Calculator(0)
    .add(10)
    .subtract(2)
    
    // This line won't work because of the argument order of `operation`:
    .operation('add', 20)
    
    .value;

In the example above, the first argument of operation is not the number being operated on. It is inconsistent with add and subtract, so will not work in chaining.