如何清除setInterval函数？ [重复]

这个问题在这里已有答案：

• Stop setInterval call in JavaScript 9个答案

`#bulb{width:100px; height: 100px; border: 1px #333 solid; margin: 20px;}
    #bulb.active{background: yellow;}`

<button type="button" id="toggle">toggle</button>
 <button type="button" id="getState">getState</button>
 <button type="button" id="off">off</button>
 <button type="button" id="on">on</button>
 <button type="button" id="blink">blink</button>

 <div id="bulb"></div>

var $ = function(el){
            return document.getElementById(el);
        };
        var bulb = $('bulb');
        var lightBulbAPI = {
            toggle : function(){
                if(bulb.className == 'active'){
                    bulb.className = '';    
                }else{
                    bulb.className = 'active';
                }
            },
            getState : function(){
                if(bulb.className == 'active'){
                    console.log("ON");  
                }else{
                    console.log("OFF"); 
                }
            },
            off : function(){
                if(bulb.className == 'active'){
                    bulb.className = '';    
                }
                bulb.className = '';
                clearInterval();
            },
            on : function(){
                bulb.className = 'active';
            },
            blink : function(){
                setInterval(function(){
                    console.log(this.off);
                    if(bulb.className == 'active'){
                        bulb.className = '';    
                    }else{
                        bulb.className = 'active';
                    }
                }, 300);
            }
        };

        $('on').addEventListener('click', lightBulbAPI.on);

        $('off').addEventListener('click', lightBulbAPI.off);   

        $('getState').addEventListener('click', lightBulbAPI.getState); 

        $('toggle').addEventListener('click', lightBulbAPI.toggle);

        $('blink').addEventListener('click', lightBulbAPI.blink);