/*
    姝ゆ??浠?extarea??楂?搴︽? height:100%; 缁ф?跨?跺??绱???楂?搴 ==> ?跺??绱?????涓?涓 position:relative; ?ㄤ?瀹?浣?textarea
    椤甸??腑??杞藉?姣???娣诲??浜?pre??绛撅?pre??绛炬??互????绱?瀛??ㄧ??骞朵?涓????锛?浣??????ㄧ┖?达?
    涓???display:none;浠?涔?绌洪?翠?涓?????
    ??浠?extarea?跺??绱???楂?搴︽????杩?pre??寮???(??extarea???㈠???ユ??瀛?锛???瀛?浼?琚?坊????re搴?涓???span??绛鹃??锛?浠ユ??ユ??寮?pre??楂?搴?

    瑕??瑰??textarea??濮????剁??楂?搴︼??????瑰??pre??padding?煎?冲???椤甸?㈠??杞芥??re???㈡坊??<br />??绛炬??负浜?璁?re??绛惧??濮??舵??涓??搴
 */
;(function ($) {

    // Constructor
    function FT(elem) {
        this.$textarea = $(elem);

        this._init();
    }

    FT.prototype = {
        _init: function () {
            var _this = this;

            // Insert wrapper elem & pre/span for textarea mirroring
            this.$textarea.wrap('<div class="flex-text-wrap" />').before('<pre class="pre"><span /><br /></pre>');

            this.$span = this.$textarea.prev().find('span');

            // Add input event listeners
            // * input for modern browsers
            // * propertychange for IE 7 & 8
            // * keyup for IE >= 9: catches keyboard-triggered undos/cuts/deletes
            // * change for IE >= 9: catches mouse-triggered undos/cuts/deletions (when textarea loses focus)
            this.$textarea.on('input propertychange keyup change', function () {
                _this._mirror();
            });

            // jQuery val() strips carriage return chars by default (see http://api.jquery.com/val/)
            // This causes issues in IE7, but a valHook can be used to preserve these chars
            $.valHooks.textarea = {
                get: function (elem) {
                    return elem.value.replace(/\r?\n/g, "\r\n");
                }
            };

            // Mirror contents once on init
            this._mirror();
        }

        // Mirror pre/span & textarea contents
        ,_mirror: function () {
            this.$span.text(this.$textarea.val());
        }
    };

    // jQuery plugin wrapper
    $.fn.flexText = function () {
        return this.each(function () {
            // Check if already instantiated on this elem
            if (!$.data(this, 'flexText')) {
                // Instantiate & store elem + string
                $.data(this, 'flexText', new FT(this));
            }
        });
    };

})(jQuery);