A4.js

var page = require('webpage').create(),
    system = require('system'),
    address, output, size;

if (system.args.length < 3 || system.args.length > 5) {
    console.log('Usage: rasterize.js URL filename [paperwidth*paperheight|paperformat] [zoom]');
    console.log('  paper (pdf output) examples: "5in*7.5in", "10cm*20cm", "A4", "Letter"');
    console.log('  image (png/jpg output) examples: "1920px" entire page, window width 1920px');
    console.log('                                   "800px*600px" window, clipped to 800x600');
    phantom.exit(1);
} else {
    address = system.args[1];
    output = system.args[2];
    page.viewportSize = {
        width: 600,
        height: 600
    };
    if (system.args.length > 3 && system.args[2].substr(-4) === ".pdf") {
        size = system.args[3].split('*');
        page.paperSize = size.length === 2 ? {
            width: size[0],
            height: size[1],
            margin: '0px'
        } : {
            format: system.args[3],
            orientation: 'portrait',
            margin: "1cm"
        };

    } else if (system.args.length > 3 && system.args[3].substr(-2) === "px") {
        size = system.args[3].split('*');
        if (size.length === 2) {
            pageWidth = parseInt(size[0], 10);
            pageHeight = parseInt(size[1], 10);
            page.viewportSize = {
                width: pageWidth,
                height: pageHeight
            };
            page.clipRect = {
                top: 0,
                left: 0,
                width: pageWidth,
                height: pageHeight
            };
        } else {
            console.log("size:", system.args[3]);
            pageWidth = parseInt(system.args[3], 10);
            pageHeight = parseInt(pageWidth * 3 / 4, 10); // it's as good an assumption as any
            console.log("pageHeight:", pageHeight);
            page.viewportSize = {
                width: pageWidth,
                height: pageHeight
            };
        }
    }
    if (system.args.length > 4) {
        page.zoomFactor = system.args[4];
    }
    page.open(address, function(status) {
        if (status !== 'success') {
            console.log('Unable to load the address!');
            phantom.exit(1);
        } else {
            window.setTimeout(function() {

                var test = page.evaluate(function () {
                    var links = document.getElementsByTagName('link');
                    for (var i = 0, len = links.length; i < len; ++i) {
                        var link = links[i];
                        if (link.rel == 'stylesheet') {
                            if (link.media == 'screen') { link.media = ''; }
                            if (link.media == 'print') { link.media = 'ignore'; }
                        }
                    }
                    console.log("removed media print");
                });

                console.log("rendering" + test);
                page.render(output);
                phantom.exit();
            }, 200);
        }
    });
}