DOMException.js

(function(idbModules) {
    'use strict';

    /**
     * Creates a native DOMException, for browsers that support it
     * @returns {DOMException}
     */
    function createNativeDOMException(name, message) {
        var e = new DOMException.prototype.constructor(0, message);
        e.name = name || 'DOMException';
        e.message = message;
        return e;
    }

    /**
     * Creates a native DOMError, for browsers that support it
     * @returns {DOMError}
     */
    function createNativeDOMError(name, message) {
        name = name || 'DOMError';
        var e = new DOMError(name, message);
        e.name === name || (e.name = name);
        e.message === message || (e.message = message);
        return e;
    }

    /**
     * Creates a generic Error object
     * @returns {Error}
     */
    function createError(name, message) {
        var e = new Error(message);
        e.name = name || 'DOMException';
        e.message = message;
        return e;
    }

    /**
     * Logs detailed error information to the console.
     * @param {string} name
     * @param {string} message
     * @param {string|Error|null} error
     */
    idbModules.util.logError = function(name, message, error) {
        if (idbModules.DEBUG) {
            if (error && error.message) {
                error = error.message;
            }

            var method = typeof(console.error) === 'function' ? 'error' : 'log';
            console[method](name + ': ' + message + '. ' + (error || ''));
            console.trace && console.trace();
        }
    };

    /**
     * Finds the error argument.  This is useful because some WebSQL callbacks
     * pass the error as the first argument, and some pass it as the second argument.
     * @param {array} args
     * @returns {Error|DOMException|undefined}
     */
    idbModules.util.findError = function(args) {
        var err;
        if (args) {
            if (args.length === 1) {
                return args[0];
            }
            for (var i = 0; i < args.length; i++) {
                var arg = args[i];
                if (arg instanceof Error || arg instanceof DOMException) {
                    return arg;
                }
                else if (arg && typeof arg.message === "string") {
                    err = arg;
                }
            }
        }
        return err;
    };

    var test, useNativeDOMException = false, useNativeDOMError = false;

    // Test whether we can use the browser's native DOMException class
    try {
        test = createNativeDOMException('test name', 'test message');
        if (test instanceof DOMException && test.name === 'test name' && test.message === 'test message') {
            // Native DOMException works as expected
            useNativeDOMException = true;
        }
    }
    catch (e) {}

    // Test whether we can use the browser's native DOMError class
    try {
        test = createNativeDOMError('test name', 'test message');
        if (test instanceof DOMError && test.name === 'test name' && test.message === 'test message') {
            // Native DOMError works as expected
            useNativeDOMError = true;
        }
    }
    catch (e) {}

    if (useNativeDOMException) {
        idbModules.DOMException = DOMException;
        idbModules.util.createDOMException = function(name, message, error) {
            idbModules.util.logError(name, message, error);
            return createNativeDOMException(name, message);
        };
    }
    else {
        idbModules.DOMException = Error;
        idbModules.util.createDOMException = function(name, message, error) {
            idbModules.util.logError(name, message, error);
            return createError(name, message);
        };
    }

    if (useNativeDOMError) {
        idbModules.DOMError = DOMError;
        idbModules.util.createDOMError = function(name, message, error) {
            idbModules.util.logError(name, message, error);
            return createNativeDOMError(name, message);
        };
    }
    else {
        idbModules.DOMError = Error;
        idbModules.util.createDOMError = function(name, message, error) {
            idbModules.util.logError(name, message, error);
            return createError(name, message);
        };
    }
}(idbModules));