magic-string

Generate a source map

This feature demonstrates how to prepend and append content to a string and generate a source map for the transformation. It's useful for tracking changes between the original and transformed code.

const MagicString = require('magic-string');
let s = new MagicString('export var answer = 42;');
s.prepend('/* hello */\n').append('\n/* world */');
console.log(s.toString());
console.log(s.generateMap({ hires: true }));

Replace content

This feature shows how to replace a specific part of the string ('answer' with 'question'). It's particularly useful for code modifications where precise control over the text is needed.

const MagicString = require('magic-string');
let s = new MagicString('export var answer = 42;');
s.overwrite(12, 17, 'question');
console.log(s.toString());

Remove content

This feature illustrates how to remove a section of the string (the 'export ' part). It's useful for cleaning up or simplifying code by removing unnecessary parts.

const MagicString = require('magic-string');
let s = new MagicString('export var answer = 42;');
s.remove(0, 7);
console.log(s.toString());