Util.js

/*
 * L.Util is a namespace for various utility functions.
 */

L.Util = {
	extend: function (/*Object*/ dest) /*-> Object*/ {	// merge src properties into dest
		var sources = Array.prototype.slice.call(arguments, 1);
		for (var j = 0, len = sources.length, src; j < len; j++) {
			src = sources[j] || {};
			for (var i in src) {
				if (src.hasOwnProperty(i)) {
					dest[i] = src[i];
				}
			}
		}
		return dest;
	},

	bind: function (fn, obj) { // (Function, Object) -> Function
		var args = arguments.length > 2 ? Array.prototype.slice.call(arguments, 2) : null;
		return function () {
			return fn.apply(obj, args || arguments);
		};
	},

	stamp: (function () {
		var lastId = 0, key = '_leaflet_id';
		return function (/*Object*/ obj) {
			obj[key] = obj[key] || ++lastId;
			return obj[key];
		};
	}()),


	// TODO refactor: remove repetition

	requestAnimFrame: (function () {
		function timeoutDefer(callback) {
			window.setTimeout(callback, 1000 / 60);
		}

		var requestFn = window.requestAnimationFrame ||
			window.webkitRequestAnimationFrame ||
			window.mozRequestAnimationFrame ||
			window.oRequestAnimationFrame ||
			window.msRequestAnimationFrame ||
			timeoutDefer;

		return function (callback, context, immediate, contextEl) {
			callback = context ? L.Util.bind(callback, context) : callback;
			if (immediate && requestFn === timeoutDefer) {
				callback();
			} else {
				return requestFn.call(window, callback, contextEl);
			}
		};
	}()),

	cancelAnimFrame: (function () {
		var requestFn = window.cancelAnimationFrame ||
			window.webkitCancelRequestAnimationFrame ||
			window.mozCancelRequestAnimationFrame ||
			window.oCancelRequestAnimationFrame ||
			window.msCancelRequestAnimationFrame ||
			clearTimeout;

		return function (handle) {
			if (!handle) { return; }
			return requestFn.call(window, handle);
		};
	}()),

	limitExecByInterval: function (fn, time, context) {
		var lock, execOnUnlock;
		
		return function wrapperFn() {
			var args = arguments;

			if (lock) {
				execOnUnlock = true;
				return;
			}

			lock = true;
			
			setTimeout(function () {
				lock = false;
				
				if (execOnUnlock) {
					wrapperFn.apply(context, args);
					execOnUnlock = false;
				}
			}, time);

			fn.apply(context, args);
		};
	},

	falseFn: function () {
		return false;
	},

	formatNum: function (num, digits) {
		var pow = Math.pow(10, digits || 5);
		return Math.round(num * pow) / pow;
	},

	setOptions: function (obj, options) {
		obj.options = L.Util.extend({}, obj.options, options);
		return obj.options;
	},

	getParamString: function (obj) {
		var params = [];
		for (var i in obj) {
			if (obj.hasOwnProperty(i)) {
				params.push(i + '=' + obj[i]);
			}
		}
		return '?' + params.join('&');
	},

	template: function (str, data) {
		return str.replace(/\{ *([\w_]+) *\}/g, function (str, key) {
			var value = data[key];
			if (!data.hasOwnProperty(key)) {
				throw new Error('No value provided for variable ' + str);
			}
			return value;
		});
	},

	emptyImageUrl: 'data:image/gif;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs='
};