Generator

script.js

var gen = function(str) {
    var g_datetime = function(flags) {
        var date = new Date();
        if (flags["<"] ^ flags[">"]) {
            var dayTicks = 86400000,
                midnight=new Date(date.getTime() - ( ( date.getTime() - ( date.getTimezoneOffset() * 60000 ) ) % dayTicks )),
                mins=~~(date.getTime() - midnight.getTime()),
                tOffset=g_number.apply(null, flags.t ? flags["<"] ? [0,mins] : [mins,dayTicks] : [0,dayTicks]),
                dOffset=g_number(1,365)*dayTicks*(flags["<"]?-1:1);
            date = new Date(midnight.getTime() + (flags.t && !flags.d ? 0 : dOffset) + tOffset);
        }
        return !(flags.d ^ flags.t)
            ? date.toLocaleString()
            : flags.d
                ? date.toLocaleDateString()
                : date.toLocaleTimeString();
    };
    var g_randstr = function(arg) {
        var str="";
        if (typeof arg == "number")
            for(var i=0;i<arg;i++) 
                str += g_number(0,35).toString(36);
        else if (arg && arg.push)
            str=arg[g_number(0,arg.length-1)];
        return str;
    }
    var g_number = function(min,max,pad) {
        var num = ~~((Math.random() * (max-min+1)) + min);
        return pad ? (pad + num).slice(-(pad.length)).replace(/^(0+)-\b/,"-$1") : num;
    };
    var g_email = function(domain) {
        domain=domain||"example.com";
        return g_randstr(10,10) + (~domain.indexOf("@") ? "" : "@") + domain;
    };
    var a_passthru = function(opt) { return opt; }
    var a_numrange = function(opt) {
        var m=_numrange(/^(?:(-?\d+)?-(-?\d+)?)?(?:([sz])(\d+)?)?$/, opt,0,100);
        return m.slice(0,2).concat(m[2] ? _padder({s:' ',z:0}[m[2]], m[3] || Math.max((m[0]+"").length,(m[1]+"").length)) : "");
    };
    var a_randstr = function(opt) {
        return ~opt.indexOf("|") ? [opt.split("|")] : _numOr(opt,g_number.apply(null,_numrange(/^(\d+)(?:-(\d+))$/, opt, 5, 5)));
    }
    var a_flags = function(opt) {
        return opt.split("").reduce(function(o,v) { o[v]=true; return o; }, {});
    }
    var _numOr = function(num,or) {
        return /^-?\d+$/.exec(num) ? Number(num) : or;
    };
    var _padder = function(char,sz) {
        for (var i=0,pad="";i<sz;i++)
            pad += char;
        return pad;
    };
    var _numrange = function(re,opt,defaultMin,defaultMax) {
        var m = re.exec(opt) || [],
            min=_numOr(m[1],defaultMin),
            max=_numOr(m[2],defaultMax);
        return [min,max].sort().concat(m.slice(3));
    }
    var generators = {
        d:g_datetime,
        n:g_number,
        e:g_email,
        s:g_randstr
    };
    var attribs = {
        d:a_flags,
        n:a_numrange,
        s:a_randstr
    };
    return str.replace(/{=(\w+)(?::([^}]*))?}/g, function(matched, name, opt) {
        name=name.toLowerCase();
		var fnGenerator = generators[name];
		var fnAttribs = attribs[name] || a_passthru;
        return fnGenerator
            ? fnGenerator.apply(null, [].concat(fnAttribs(opt || "")))
            : matched;
    	}
    );
};