<script type="text/javascript">
        <!--

    var foo = function(){ this.init.apply(this,arguments);};

    foo.prototype = {
        init:function(_name){
            this.name = _name;
            this.addEvent('click',document,this.say,this,'hello world!');
        },
        say:function(_ev,_word){
            alert(this.name +':' +_word);
            this.stop();
            this.onSay(_word);
        },
        stop:function(){
            this.removeEvent('click',document,this.say);
        },
        addEvent:function(_event,_element,_fn,_scope,_args){
            var args = Array.prototype.slice.call(arguments, 0);  
            ev = args.shift(),
            element = args.shift(),
            fn = args.shift(),
            scope = args.length>0?args.shift():window;
            element['e'+ev+fn] =  function(_ev){
                _ev == _ev || window.event;
                args.unshift(_ev);
                fn.apply(scope,args);
            };
            if (element.addEventListener) {
                element.addEventListener(ev, element['e'+ev+fn], false);
            } else if (element.attachEvent) {
                element.attachEvent("on" +ev, element['e'+ev+fn]);
            }
        },
        removeEvent:function(_event,_element,_fn){
            if (_element.removeEventListener) {
                _element.removeEventListener(_event, _element['e'+_event+_fn], false);
            } else if (_element.detachEvent) {
                _element.detachEvent("on" +_event, _element['e'+_event+_fn]);
            }
            try {
                delete _element['e'+_event+_fn];
            }catch(_ex){
                _element['e'+_event+_fn] = null;
            }
        },
        onSay:function(){}

    }


var a = new foo('llinzzi');
a.onSay = function(_word){
    alert('事件:'+this.name +'刚说了'+ _word);
}

    var foo = function(){ this.init.apply(this,arguments);};

    foo.prototype = {
        init:function(_name){
            this.name = _name;
            this.addEvent('click',document,this.say,this,'hello world!');
        },
        say:function(_ev,_word){
            alert(this.name +':' +_word);
            this.stop();
            this._onSay(_word);
        },
        stop:function(){
            this.removeEvent('click',document,this.say);
        },
        addEvent:function(_event,_element,_fn,_scope,_args){
            var args = Array.prototype.slice.call(arguments, 0);  
            ev = args.shift(),
            element = args.shift(),
            fn = args.shift(),
            scope = args.length>0?args.shift():window;
            element['e'+ev+fn] =  function(_ev){
                _ev == _ev || window.event;
                args.unshift(_ev);
                fn.apply(scope,args);
            };
            if (element.addEventListener) {
                element.addEventListener(ev, element['e'+ev+fn], false);
            } else if (element.attachEvent) {
                element.attachEvent("on" +ev, element['e'+ev+fn]);
            }
        },
        removeEvent:function(_event,_element,_fn){
            if (_element.removeEventListener) {
                _element.removeEventListener(_event, _element['e'+_event+_fn], false);
            } else if (_element.detachEvent) {
                _element.detachEvent("on" +_event, _element['e'+_event+_fn]);
            }
            try {
                delete _element['e'+_event+_fn];
            }catch(_ex){
                _element['e'+_event+_fn] = null;
            }
        },
        _onSay:function(){
            if(!this._onSayArray) return;    
            for(var i=0; i<this._onSayArray.length; i++){
                this._onSayArray[i].apply(this,arguments);
            }
        },
        addOnSay:function(_fn){
            if(!this._onSayArray) this._onSayArray = new Array();
            this._onSayArray.push(_fn);
        }
    }


var a = new foo('llinzzi');
a.addOnSay(function(_word){
    alert('事件1:'+this.name +'刚说了'+ _word);
});
a.addOnSay(function(_word){
    alert('事件2:'+this.name +'刚说了'+ _word);
});

    var foo = function(){ this.init.apply(this,arguments);};

    foo.prototype = {
        init:function(_name){
            this.name = _name;
            this.addEvent('click',document,this.say,this,'hello world!');
        },
        say:function(_ev,_word){
            this.fireEvent('saybefore',_word);
            alert(this.name +':' +_word);
            this.stop();
            this.fireEvent('sayafter',_word);
        },
        stop:function(){
            this.removeEvent('click',document,this.say);
        },
        addEvent:function(_event,_element,_fn,_scope,_args){
            var args = Array.prototype.slice.call(arguments, 0);  
            ev = args.shift(),
            element = args.shift(),
            fn = args.shift(),
            scope = args.length>0?args.shift():window;
            element['e'+ev+fn] =  function(_ev){
                _ev == _ev || window.event;
                args.unshift(_ev);
                fn.apply(scope,args);
            };
            if (element.addEventListener) {
                element.addEventListener(ev, element['e'+ev+fn], false);
            } else if (element.attachEvent) {
                element.attachEvent("on" +ev, element['e'+ev+fn]);
            }
        },
        removeEvent:function(_event,_element,_fn){
            if (_element.removeEventListener) {
                _element.removeEventListener(_event, _element['e'+_event+_fn], false);
            } else if (_element.detachEvent) {
                _element.detachEvent("on" +_event, _element['e'+_event+_fn]);
            }
            try {
                delete _element['e'+_event+_fn];
            }catch(_ex){
                _element['e'+_event+_fn] = null;
            }
        },
        fireEvent:function(){
            var args = Array.prototype.slice.call(arguments, 0);  
            var _event = args.shift();
            if(!this.cusEvents) return;
            if(!this.cusEvents[_event]) return;
            for(var i=0; i<this.cusEvents[_event].length; i++){
                this.cusEvents[_event][i].apply(this,args);
            }
        },
        catchEvent:function(_event,_fn){
            if(!this.cusEvents) this.cusEvents = {}
            if(!this.cusEvents[_event]) this.cusEvents[_event] = new Array();
            this.cusEvents[_event].push(_fn);
        }
    }


var a = new foo('llinzzi');

a.catchEvent('saybefore',function(_word){
    alert('事件1:'+this.name +'想说'+ _word);
});

a.catchEvent('sayafter',function(_word){
    alert('事件2:'+this.name +'刚说了'+ _word);
});

    EventHelper = {
        Events:{Dom:{},Custom:{}},
        addEvent:function(_object,_event,_fn,_scope,_args){
            var args = Array.prototype.slice.call(arguments, 0),  
                obj = args.shift(),
                ev = args.shift(),
                fn = args.shift(),
                scope = args.length>0?args.shift():window;
            var eType = obj.nodeType?'Dom':'Custom';
            var fun;
            if(eType=='Dom'){
                sfn = function(_ev){
                    _ev == _ev || window.event;
                    args.unshift(_ev);
                    fn.apply(scope,args);
                }
                if (obj.addEventListener) {
                    obj.addEventListener(ev,sfn, false);
                } else if (obj.attachEvent) {
                    obj.attachEvent("on" +ev,sfn);
                }
            }else {
                sfn = function(){
                    var __sargs = Array.prototype.slice.call(arguments, 0);
                    var _sargs = __sargs.concat(args);
                    fn.apply(scope,_sargs);
                }    
            }
            fun = { fn:fn,sfn:sfn };
            this.Events[eType][obj] = this.Events[eType][obj] || {};
            this.Events[eType][obj][ev] = this.Events[eType][obj][ev] || new Array();
            this.Events[eType][obj][ev].push(fun);
        },
        removeEvent:function(_object,_event,_fn){
            var obj = _object,
                ev = _event,
                fn = _fn;
            var eType = obj.nodeType?'Dom':'Custom';
            if(!this.Events[eType][obj]) return;

            var fun;
            for( var i=0; i<this.Events[eType][obj][ev].length;i++){
                if(fn == this.Events[eType][obj][ev][i].fn){
                    fun = this.Events[eType][obj][ev][i].sfn;
                    this.Events[eType][obj][ev].splice(i,1);
                    break;
                }
            }
            if(eType=='Dom'){
                if (obj.removeEventListener) {
                    obj.removeEventListener(ev, fun, false);
                } else if (obj.detachEvent) {
                    obj.detachEvent("on" + ev, fun);
                }
            }

        },
        fireEvent:function(_object,_event){
            var args = Array.prototype.slice.call(arguments, 0),  
                obj = args.shift(),
                ev = args.shift();
            var eType = 'Custom';
            if((!this.Events[eType][obj]) || (!this.Events[eType][obj][ev])) return;
            for(var i=0; i<this.Events[eType][obj][ev].length; i++){
                this.Events[eType][obj][ev][i].sfn.apply(window,args);
            }
        }
    }

        var foo = function(){ this.init.apply(this,arguments);};
        
        foo.prototype = {
            init:function(_name){
                 this.name = _name;
                 this.addEvent('click',document,this.say);
            },
            say:function(_ev){
                alert(this.name);
                this.stop();
            },
            stop:function(){
                 this.removeEvent('click',document,this.say);
          },
            addEvent:function(_event,_element,_fn){
                if (_element.addEventListener) {
                    _element.addEventListener(_event, _fn, false);
                } else if (_element.attachEvent) {
                    _element.attachEvent("on" +_event,_fn);
                }
            },
            removeEvent:function(_event,_element,_fn){
                if (_element.removeEventListener) {
                    _element.removeEventListener(_event, _fn, false);
                } else if (_element.detachEvent) {
                    _element.detachEvent("on" +_event, _fn);
                }
            }
        }

        var a = new foo('llinzzi');

        var foo = function(){ this.init.apply(this,arguments);};
        
        foo.prototype = {
            init:function(_name){
                 this.name = _name;
                 this.addEvent('click',document,this.say,this,'hello world!');
            },
            say:function(_ev,_word){
                alert(this.name +':' +_word);
                this.stop();
            },
            stop:function(){
                 this.removeEvent('click',document,this.say);
          },
            addEvent:function(_event,_element,_fn,_scope,_args){
                var args = this._toArray(arguments),
                    ev = args.shift(),
                    element = args.shift(),
                    fn = args.shift(),
                    scope = args.length>0?args.shift():window;
                element['e'+ev+fn] =  function(_ev){
                    _ev == _ev || window.event;
                    args.unshift(_ev);
                    fn.apply(scope,args);
                };
                if (element.addEventListener) {
                    element.addEventListener(ev, element['e'+ev+fn], false);
                } else if (element.attachEvent) {
                    element.attachEvent("on" +ev, element['e'+ev+fn]);
                }
            },
            removeEvent:function(_event,_element,_fn){
                if (_element.removeEventListener) {
                    _element.removeEventListener(_event, _element['e'+_event+_fn], false);
                } else if (_element.detachEvent) {
                    _element.detachEvent("on" +_event, _element['e'+_event+_fn]);
                }
                try {
                    delete _element['e'+_event+_fn];
                }catch(_ex){
                    _element['e'+_event+_fn] = null;
                }
            },
            _toArray:function(iterable){
                if (!iterable) return [];
                if (iterable.toArray) return iterable.toArray();
                var length = iterable.length || 0, results = new Array(length);
                while (length--) results[length] = iterable[length];
                return results;
            }
        }


        var a = new foo('llinzzi');

    var style = _element.currentStyle || document.defaultView.getComputedStyle(_element,null);
        var value = style[_property]

    var px = parseInt(pt)*((1/72)*screen.deviceXDPI) +'px';

var defaultLineheight = fontsize*(7/6);

(function(){

var AutoOverHider = function() { this.init.apply(this,arguments);};

AutoOverHider.prototype = {
    init:function(_element,_maxLine){
        this.element = document.getElementById(_element);
        if(_maxLine) this.hide(_maxLine);
    },
    hide:function(_maxLine){
        this.maxLine = _maxLine;
        var lineHeight = this._getStyle('lineHeight');
        if(lineHeight=='normal') { lineHeight = 7/6+'';}
        if(lineHeight.substr(lineHeight.length-2)!='px')    lineHeight = lineHeight * parseInt(this._getStyle('fontSize')) + 'px';
        var paddingHeight = this._getStyle('paddingBottom');
        alert(paddingHeight);
        this.height =  this.maxLine * parseInt(lineHeight) - parseInt(paddingHeight);
        this.element.style.height = this.height  + 'px';
        this.element.style.overflow = 'hidden';
    },
    show:function(){
        this.element.style.height = 'auto';
    },
    _getStyle:function(_property,_element){
        _element = _element||this.element;
        var style = _element.currentStyle || document.defaultView.getComputedStyle(_element,null);
        var value = style[_property]
        if(/*@cc_on!@*/0 ) {
            if(value.substr(value.length-2)=='pt')
                value = parseInt(value)*((1/72)*screen.deviceXDPI) +'px';
        }
        return value;
    }
};


})()

<div id="t1">
千余字
</div>

var a1 = new AutoOverHider('t1');
a1.hide(5);
或者
var a1 = new AutoOverHider('t1'，5);

body:nth-of-type(1) p{
   color: #333333;
}