less.js/lib/less-browser/add-default-options.js

var addDataAttr = require('./utils').addDataAttr,
    browser = require('./browser');

module.exports = function(window, options) {

    // use options from the current script tag data attribues
    addDataAttr(options, browser.currentScript(window));

    if (options.isFileProtocol === undefined) {
        options.isFileProtocol = /^(file|(chrome|safari)(-extension)?|resource|qrc|app):/.test(window.location.protocol);
    }

    // Load styles asynchronously (default: false)
    //
    // This is set to `false` by default, so that the body
    // doesn't start loading before the stylesheets are parsed.
    // Setting this to `true` can result in flickering.
    //
    options.async = options.async || false;
    options.fileAsync = options.fileAsync || false;

    // Interval between watch polls
    options.poll = options.poll || (options.isFileProtocol ? 1000 : 1500);

    options.env = options.env || (window.location.hostname == '127.0.0.1' ||
        window.location.hostname == '0.0.0.0'   ||
        window.location.hostname == 'localhost' ||
        (window.location.port &&
            window.location.port.length > 0)      ||
        options.isFileProtocol                   ? 'development'
        : 'production');

    var dumpLineNumbers = /!dumpLineNumbers:(comments|mediaquery|all)/.exec(window.location.hash);
    if (dumpLineNumbers) {
        options.dumpLineNumbers = dumpLineNumbers[1];
    }

    if (options.useFileCache === undefined) {
        options.useFileCache = true;
    }

    if (options.onReady === undefined) {
        options.onReady = true;
    }

    // TODO: deprecate and remove 'inlineJavaScript' thing - where it came from at all?
    options.javascriptEnabled = (options.javascriptEnabled || options.inlineJavaScript) ? true : false;

};