/node_modules/hammerjs/src/utils.js

var VENDOR_PREFIXES = ['', 'webkit', 'Moz', 'MS', 'ms', 'o'];
var TEST_ELEMENT = document.createElement('div');

var TYPE_FUNCTION = 'function';

var round = Math.round;
var abs = Math.abs;
var now = Date.now;

/**
 * set a timeout with a given scope
 * @param {Function} fn
 * @param {Number} timeout
 * @param {Object} context
 * @returns {number}
 */
function setTimeoutContext(fn, timeout, context) {
    return setTimeout(bindFn(fn, context), timeout);
}

/**
 * if the argument is an array, we want to execute the fn on each entry
 * if it aint an array we don't want to do a thing.
 * this is used by all the methods that accept a single and array argument.
 * @param {*|Array} arg
 * @param {String} fn
 * @param {Object} [context]
 * @returns {Boolean}
 */
function invokeArrayArg(arg, fn, context) {
    if (Array.isArray(arg)) {
        each(arg, context[fn], context);
        return true;
    }
    return false;
}

/**
 * walk objects and arrays
 * @param {Object} obj
 * @param {Function} iterator
 * @param {Object} context
 */
function each(obj, iterator, context) {
    var i;

    if (!obj) {
        return;
    }

    if (obj.forEach) {
        obj.forEach(iterator, context);
    } else if (obj.length !== undefined) {
        i = 0;
        while (i < obj.length) {
            iterator.call(context, obj[i], i, obj);
            i++;
        }
    } else {
        for (i in obj) {
            obj.hasOwnProperty(i) && iterator.call(context, obj[i], i, obj);
        }
    }
}

/**
 * wrap a method with a deprecation warning and stack trace
 * @param {Function} method
 * @param {String} name
 * @param {String} message
 * @returns {Function} A new function wrapping the supplied method.
 */
function deprecate(method, name, message) {
    var deprecationMessage = 'DEPRECATED METHOD: ' + name + '\n' + message + ' AT \n';
    return function() {
        var e = new Error('get-stack-trace');
        var stack = e && e.stack ? e.stack.replace(/^[^\(]+?[\n$]/gm, '')
            .replace(/^\s+at\s+/gm, '')
            .replace(/^Object.<anonymous>\s*\(/gm, '{anonymous}()@') : 'Unknown Stack Trace';

        var log = window.console && (window.console.warn || window.console.log);
        if (log) {
            log.call(window.console, deprecationMessage, stack);
        }
        return method.apply(this, arguments);
    };
}

/**
 * extend object.
 * means that properties in dest will be overwritten by the ones in src.
 * @param {Object} target
 * @param {...Object} objects_to_assign
 * @returns {Object} target
 */
var assign;
if (typeof Object.assign !== 'function') {
    assign = function assign(target) {
        if (target === undefined || target === null) {
            throw new TypeError('Cannot convert undefined or null to object');
        }

        var output = Object(target);
        for (var index = 1; index < arguments.length; index++) {
            var source = arguments[index];
            if (source !== undefined && source !== null) {
                for (var nextKey in source) {
                    if (source.hasOwnProperty(nextKey)) {
                        output[nextKey] = source[nextKey];
                    }
                }
            }
        }
        return output;
    };
} else {
    assign = Object.assign;
}

/**
 * extend object.
 * means that properties in dest will be overwritten by the ones in src.
 * @param {Object} dest
 * @param {Object} src
 * @param {Boolean} [merge=false]
 * @returns {Object} dest
 */
var extend = deprecate(function extend(dest, src, merge) {
    var keys = Object.keys(src);
    var i = 0;
    while (i < keys.length) {
        if (!merge || (merge && dest[keys[i]] === undefined)) {
            dest[keys[i]] = src[keys[i]];
        }
        i++;
    }
    return dest;
}, 'extend', 'Use `assign`.');

/**
 * merge the values from src in the dest.
 * means that properties that exist in dest will not be overwritten by src
 * @param {Object} dest
 * @param {Object} src
 * @returns {Object} dest
 */
var merge = deprecate(function merge(dest, src) {
    return extend(dest, src, true);
}, 'merge', 'Use `assign`.');

/**
 * simple class inheritance
 * @param {Function} child
 * @param {Function} base
 * @param {Object} [properties]
 */
function inherit(child, base, properties) {
    var baseP = base.prototype,
        childP;

    childP = child.prototype = Object.create(baseP);
    childP.constructor = child;
    childP._super = baseP;

    if (properties) {
        assign(childP, properties);
    }
}

/**
 * simple function bind
 * @param {Function} fn
 * @param {Object} context
 * @returns {Function}
 */
function bindFn(fn, context) {
    return function boundFn() {
        return fn.apply(context, arguments);
    };
}

/**
 * let a boolean value also be a function that must return a boolean
 * this first item in args will be used as the context
 * @param {Boolean|Function} val
 * @param {Array} [args]
 * @returns {Boolean}
 */
function boolOrFn(val, args) {
    if (typeof val == TYPE_FUNCTION) {
        return val.apply(args ? args[0] || undefined : undefined, args);
    }
    return val;
}

/**
 * use the val2 when val1 is undefined
 * @param {*} val1
 * @param {*} val2
 * @returns {*}
 */
function ifUndefined(val1, val2) {
    return (val1 === undefined) ? val2 : val1;
}

/**
 * addEventListener with multiple events at once
 * @param {EventTarget} target
 * @param {String} types
 * @param {Function} handler
 */
function addEventListeners(target, types, handler) {
    each(splitStr(types), function(type) {
        target.addEventListener(type, handler, false);
    });
}

/**
 * removeEventListener with multiple events at once
 * @param {EventTarget} target
 * @param {String} types
 * @param {Function} handler
 */
function removeEventListeners(target, types, handler) {
    each(splitStr(types), function(type) {
        target.removeEventListener(type, handler, false);
    });
}

/**
 * find if a node is in the given parent
 * @method hasParent
 * @param {HTMLElement} node
 * @param {HTMLElement} parent
 * @return {Boolean} found
 */
function hasParent(node, parent) {
    while (node) {
        if (node == parent) {
            return true;
        }
        node = node.parentNode;
    }
    return false;
}

/**
 * small indexOf wrapper
 * @param {String} str
 * @param {String} find
 * @returns {Boolean} found
 */
function inStr(str, find) {
    return str.indexOf(find) > -1;
}

/**
 * split string on whitespace
 * @param {String} str
 * @returns {Array} words
 */
function splitStr(str) {
    return str.trim().split(/\s+/g);
}

/**
 * find if a array contains the object using indexOf or a simple polyFill
 * @param {Array} src
 * @param {String} find
 * @param {String} [findByKey]
 * @return {Boolean|Number} false when not found, or the index
 */
function inArray(src, find, findByKey) {
    if (src.indexOf && !findByKey) {
        return src.indexOf(find);
    } else {
        var i = 0;
        while (i < src.length) {
            if ((findByKey && src[i][findByKey] == find) || (!findByKey && src[i] === find)) {
                return i;
            }
            i++;
        }
        return -1;
    }
}

/**
 * convert array-like objects to real arrays
 * @param {Object} obj
 * @returns {Array}
 */
function toArray(obj) {
    return Array.prototype.slice.call(obj, 0);
}

/**
 * unique array with objects based on a key (like 'id') or just by the array's value
 * @param {Array} src [{id:1},{id:2},{id:1}]
 * @param {String} [key]
 * @param {Boolean} [sort=False]
 * @returns {Array} [{id:1},{id:2}]
 */
function uniqueArray(src, key, sort) {
    var results = [];
    var values = [];
    var i = 0;

    while (i < src.length) {
        var val = key ? src[i][key] : src[i];
        if (inArray(values, val) < 0) {
            results.push(src[i]);
        }
        values[i] = val;
        i++;
    }

    if (sort) {
        if (!key) {
            results = results.sort();
        } else {
            results = results.sort(function sortUniqueArray(a, b) {
                return a[key] > b[key];
            });
        }
    }

    return results;
}

/**
 * get the prefixed property
 * @param {Object} obj
 * @param {String} property
 * @returns {String|Undefined} prefixed
 */
function prefixed(obj, property) {
    var prefix, prop;
    var camelProp = property[0].toUpperCase() + property.slice(1);

    var i = 0;
    while (i < VENDOR_PREFIXES.length) {
        prefix = VENDOR_PREFIXES[i];
        prop = (prefix) ? prefix + camelProp : property;

        if (prop in obj) {
            return prop;
        }
        i++;
    }
    return undefined;
}

/**
 * get a unique id
 * @returns {number} uniqueId
 */
var _uniqueId = 1;
function uniqueId() {
    return _uniqueId++;
}

/**
 * get the window object of an element
 * @param {HTMLElement} element
 * @returns {DocumentView|Window}
 */
function getWindowForElement(element) {
    var doc = element.ownerDocument || element;
    return (doc.defaultView || doc.parentWindow || window);
}