【转载】 input 和 textarea 最大文字限定插件

/* input 和 textarea 最大文字限定插件
 * 修改版, 一个中文表示1一个字, 一个英文半个字;
 * TextLimit - jQuery plugin for counting and limiting characters for input and textarea fields
 
 * pass '-1' as speed if you don't want the char-deletion effect. (don't just put 0)
 * Example: jQuery("Textarea").textlimit('span.counter',256)
 *
 * $Version: 2009.07.25 +r2
 * Copyright (c) 2009 Yair Even-Or
 * vsync.design@gmail.com
*/
String.prototype.getBytes = function () {
    var cArr = this.match(/[^\x00-\xff]/ig);
    return this.length + (cArr == null ? 0 : cArr.length);
};
(function(jQuery) {
    jQuery.fn.textlimit=function(counter_el, thelimit, speed) {
        var charDelSpeed = speed || 15;
        var toggleCharDel = speed != -1;
        var toggleTrim = true;
        var that = this[0];
        var isCtrl = false
        updateCounter();
          
        function updateCounter(){
            if(typeof that == "object")
                jQuery(counter_el).text(thelimit - Math.ceil(that.value.getBytes()/2));
        };
          
        this.keydown (function(e){ 
            if(e.which == 17) isCtrl = true;
            var ctrl_a = (e.which == 65 && isCtrl == true) ? true : false; // detect and allow CTRL + A selects all.
            var ctrl_v = (e.which == 86 && isCtrl == true) ? true : false; // detect and allow CTRL + V paste.
            // 8 is 'backspace' and 46 is 'delete'
            if( this.value.length >= thelimit && e.which != '8' && e.which != '46' && ctrl_a == false && ctrl_v == false)
                e.preventDefault();
        })
        .keyup (function(e){
            updateCounter();
            if(e.which == 17)
                isCtrl=false;
  
            if( this.value.length >= thelimit && toggleTrim ){
                if(toggleCharDel){
                    // first, trim the text a bit so the char trimming won't take forever
                    // Also check if there are more than 10 extra chars, then trim. just in case.
                    if ( (this.value.length - thelimit) > 10 )
                        that.value = that.value.substr(0,thelimit+100);
                    var init = setInterval
                        
                            function(){ 
                                if( that.value.length <= thelimit ){
                                    init = clearInterval(init); updateCounter() 
                                }
                                else{
                                    // deleting extra chars (one by one)
                                    that.value = that.value.substring(0,that.value.length-1); jQuery(counter_el).text(Math.ceil(that.value.getBytes()/2));
                                }
                            } ,charDelSpeed 
                        );
                }
                else this.value = that.value.substr(0,thelimit);
            }
        });
          
    };
})(jQuery);
posted @ 2011-12-22 18:15  火腿骑士  阅读(206)  评论(0编辑  收藏  举报