extend函数

合并函数，实现将第一个参数之后的所有对象合并至第一个参数对象中。

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// @function extend(dest: Object, src?: Object): Object
// Merges the properties of the `src` object (or multiple objects)
// into `dest` object and returns the latter. Has an `L.extend` shortcut.
function extend(dest) {
    var i, j, len, src;
    for (j = 1, len = arguments.length; j < len; j++) {
        src = arguments[j];
        for (i in src) {
            dest[i] = src[i];
        }
    }
    return dest;
}

creat函数

creat函数为Object.create函数的polyfill, 创建一个新的对象

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// @function create(proto: Object, properties?: Object): Object
// Compatibility polyfill for [Object.create]
// (https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object/create)
var create = Object.create || (function () {
    function F() {}
    return function (proto) {
        F.prototype = proto;
        return new F();
    };
})();

bind函数

bind函数用于绑定函数上下文，类似与Function.prototype.bind

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// @function bind(fn: Function, …): Function
// Returns a new function bound to the arguments passed, like 
// [Function.prototype.bind](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Function/bind).
// Has a `L.bind()` shortcut.
function bind(fn, obj) {
    var slice = Array.prototype.slice;
    if (fn.bind) {
        return fn.bind.apply(fn, slice.call(arguments, 1));
    }
    var args = slice.call(arguments, 2);
    return function () {
        return fn.apply(obj, args.length ? args.concat(slice.call(arguments)) : arguments);
    };
}

temlape函数

leaflet的简单的模板函数， 支持将对象{a: 'foo', b: 'bar'}的值填充至'Hello {a}, {b}'这样的模板字符串

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var templateRe = /\{ *([\w_\-]+) *\}/g;
// @function template(str: String, data: Object): String
// Simple templating facility, accepts a template string of the form `'Hello {a}, {b}'`
// and a data object like `{a: 'foo', b: 'bar'}`, returns evaluated string
// `('Hello foo, bar')`. You can also specify functions instead of strings for
// data values — they will be evaluated passing `data` as an argument.
function template(str, data) {
    return str.replace(templateRe, function (str, key) {
        var value = data[key];
        if (value === undefined) {
            throw new Error('No value provided for variable ' + str);
        } else if (typeof value === 'function') {
            value = value(data);
        }
        return value;
    });
}

isArray函数

判断对象是否为数组的工具函数，与Array.isArray的功能兼容

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// @function isArray(obj): Boolean
// Compatibility polyfill for 
//[Array.isArray](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray)
var isArray = Array.isArray || function (obj) {
    return (Object.prototype.toString.call(obj) === '[object Array]');
};

indexOf函数

用于匹配元素出现在数组中的位置，未匹配则返回-1,与Array.indexOf兼容

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// @function indexOf(array: Array, el: Object): Number
// Compatibility polyfill for 
// [Array.prototype.indexOf](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf)
function indexOf(array, el) {
    for (var i = 0; i < array.length; i++) {
        if (array[i] === el) { return i; }
    }
    return -1;
}