Node script that converts double quotes to single quotes in JavaScript files.

singlequote.js

// Taken from http://ariya.ofilabs.com/2012/02/from-double-quotes-to-single-quotes.html
// Usage:
// $ node singlequote.js <input> [output]

(function () {
    'use strict';
    var fs = require('fs'),
        esprima = require('esprima'),
        input = process.argv[2],
        output = process.argv[3] || input,
        offset = 0,
        content = fs.readFileSync(input, 'utf-8'),
        tokens = esprima.parse(content, { tokens: true, range: true }).tokens;

    function convert(literal) {
        var result = literal.substring(1, literal.length - 1);
        result = result.replace(/'/g, '"');
        result = result.replace(/\\"/g, '"');
        return '\'' + result + '\'';
    }

    tokens.forEach(function (token) {
        var str;
        if (token.type === 'String' && token.value[0] !== '\'') {
            str = convert(token.value);
            content = content.substring(0, offset + token.range[0]) + str +
                content.substring(offset + token.range[1], content.length);
            offset += (str.length - token.value.length);
        }
    });
    fs.writeFileSync(output, content);
}());

Nice! Works great. I would just document that you need esprima installed.