conversant/ad-libs.js

/**
 * @module canHas
 */

'use strict';

/**
 * @desc Can this object use this property?
 * @static
 * @param obj
 * @param propertyName
 * @returns {Boolean}
 * @example
 * ```js
 * var can = require('adlibs/lib/canHas').can;
 * ```
 */
var can = function (obj, propertyName) {
    return typeof obj[propertyName] !== 'undefined';
};

/**
 * @desc Does this window have this object in it?
 * @static
 * @param globalObjectName
 * @param [scope] Alternatively, you can call "run" with a more sane method signature.
 * @returns {*}
 * @example
 * ```js
 * var has = require('adlibs/lib/canHas').has;
 * ```
 */
var has = function (globalObjectName, scope) {
    scope = scope || window;
    return can(scope, globalObjectName) ? scope[globalObjectName] : false;
};

/**
 * @desc Check to see if this object owns the method as opposed to just inheriting it from another object.
 * @static
 * @param obj
 * @param propertyName
 * @returns {Boolean}
 */
var own = function (obj, propertyName) {
    return obj.hasOwnProperty(propertyName);
};

/**
 * @desc Return a runnable method by default.
 * @static
 * @param obj - Scope to use, or method to run when not providing a method as the second param.
 * @param [methodName] The method to check for.
 * @returns {Function}
 */
var run = function (obj, methodName) {
    var defaultRunnable = function () { return false;},
        runnable = methodName ? obj[methodName] : window[obj];

    return typeof runnable === 'function' ? runnable : defaultRunnable;
};

/**
 * @desc For each in, shorthanded because manually writing hasOwnProperty each and every time is not a good use of time.
 * @static
 * @param obj
 * @param callback
 */
var forIn = function (obj, callback) {
    var property;
    for (property in obj) {
        if (obj.hasOwnProperty(property)) {
            if (callback(property, obj[property]) === false) {
                break;
            }
        }
    }
};

/**
 * @desc A substitute for Object.keys for when browsers don't attempt to convert non-objects to arrays
 * @static
 * @param obj
 * @returns {*}
 */
var keys = function (obj){
    if (obj) {
        switch (typeof obj){
            case 'object':
                return Object.keys(obj);
            case 'string':
                return obj.split('');
            default:
                return [];
        }
    } else {
        throw new TypeError('Cannot convert null or undefined to object');
    }

};

module.exports = {
    can: can,
    has: has,
    run: run,
    own: own,
    forIn: forIn,
    keys: keys
};