This is similar to Python's "textwrap.dedent" function

dedent.js

function dedent(text) {
    var re_whitespace = /^([ \t]*)(.*)\n/gm;
    var l, m, i;

    while ((m = re_whitespace.exec(text)) !== null) {
        if (!m[2]) continue;

        if (l = m[1].length) {
            i = (i !== undefined) ? Math.min(i, l) : l;
        } else break;
    }

    if (i)
        text = text.replace(new RegExp('^[ \t]{' + i + '}(.*\n)', 'gm'), '$1');

    return text;
}