// http://joel.net/logging-errors-with-elmah-in-asp.net-mvc-3--part-5--javascript, with modifications
var logErrorUrl = "/handlers/LogClientErrors.ashx";

function logError(ex, stack) {

    if (ex == null) {
        return;
    }

    if (logErrorUrl == null) {        
        return;
    }

    var url = ex.fileName != null ? ex.fileName : document.location;
    if (stack == null && ex.stack != null) stack = ex.stack;

    // format output
    var out = ex.message != null ? ex.name + ": " + ex.message : ex;
    out += ": at document path '" + url + "'.";
    if (stack != null) out += "\n  at " + stack.join("\n  at ");

    if (out.indexOf("uncaught exception:") != -1) {
        // Saw tens of thousands of errors from one user that seem to be related to a bad Firefox plug-in (RoboForm).
        // This is an attempt to filter out those errors and not call to the server when 
        // this type of error is detected.
        return;
    }

    // send error message
    $.ajax({
        type: 'POST',
        url: logErrorUrl,
        data: { message: out }
    });
}

Function.prototype.trace = function() {
    var trace = [];
    var current = this;
    while (current) {
        trace.push(current.signature());
        current = current.caller;
    }
    return trace;
}

Function.prototype.signature = function() {
    var signature = {
        name: this.getName(),
        params: [],
        toString: function() {
            var params = this.params.length > 0 ?
                "'" + this.params.join("', '") + "'" : "";
            return this.name + "(" + params + ")"
        }
    };
    if (this.arguments) {
        for (var x = 0; x < this.arguments.length; x++)
            signature.params.push(this.arguments[x]);
    }
    return signature;
}

Function.prototype.getName = function() {
    if (this.name)
        return this.name;
    var definition = this.toString().split("\n")[0];
    var exp = /^function ([^\s(]+).+/;
    if (exp.test(definition))
        return definition.split("\n")[0].replace(exp, "$1") || "anonymous";
    return "anonymous";
}

window.onerror = function(msg, url, line) {
    try {
        logError(msg, arguments.callee.trace())
    }
    catch (e) {
    };
}