argum/argum.js

A package for getting command line arguments in a simple way.

/**
 * Given a prefix of a parameter it returns the value of that parameter.
 * Note that the prefix and parameter need to be separated by '=' sign
 * in order for this function to work.
 *
 * @param prefix {string} the prefix with which the parameter starts
 * @param required whether or not that parameter is required
 * @param defaultValue if required is set to false this the value that will be returned if the parameter is not passed to the process
 * @returns {*}
 */
exports.get = function (prefix, required, defaultValue) {
    var found = false;
    var value = defaultValue;

    // loop through all arguments passed to the process
    for (var i = 0; i < process.argv.length; i++)
    {
        if (process.argv[i].indexOf(prefix) == 0)
        {
            // parameter found
            found = true;

            if (process.argv[i].indexOf('=') == -1)
            {
                // equals sign not found
                throw new Error('Equals sign not found. Parameter\'s name and value are required to be separated by equals sign.');
            }
            else
            {
                var start = process.argv[i].indexOf('=') + 1;
                var end = process.argv[i].length;
                value = process.argv[i].slice(start, end); // get the value of the parameter
                break;
            }
        }
    }

    // if required but not found print an error message
    // out and terminate the process
    if (required && !found)
    {
        throw new Error('Required paramater ' + prefix + ' not passed in.');
    }

    return value;
};

/**
 * Searches for argument in object if found returns the value
 * if not found it either raises an error or returns the specified
 * return value
 *
 * @param object the object to search in
 * @param argument the argument to search for
 * @param required if the argument is required
 * @param defaultValue the default value in case the argument is not required and not found
 * @returns {*}
 */
exports.object = function(object, argument, required, defaultValue)
{
    if (typeof object !== 'object')
    {
        throw new Error('First argument is not an object.');
    }

    if (argument in object)
    {
        return object[argument];
    }
    else
    {
        if (required)
        {
            throw new Error('Required parameter missing: ' + argument);
        }
        else if (defaultValue)
        {
            return defaultValue;
        }
        else
        {
            return false;
        }
    }
}