在setInterval中執行this.function

Question

我想在撥打this.start時每this.delay ms打電話this.cycle。 當然，這是行不通的：

function Timer(delay, repetitions){ 
 
    this.delay = delay; 
 
    this.maxrep = repetitions; 
 
    this.rep = 0; 
 

 
    this.start = function(){ 
 
    this.interval = setInterval(function(){ 
 
     this.cycle(); 
 
    },this.delay); 
 
    } 
 

 
    this.cycle = function(){ 
 
    this.rep++; 
 
    console.log(this.rep); 
 
    if(this.rep >= this.max){ 
 
     clearInterval(this.interval); 
 
    } 
 
    } 
 
}

Answer 1

一個問題，我可以看到的是，this定時器功能裏面是不是這樣，你認爲它是。

因此，無論

var me = this 
this.start = function(){ 
    this.interval = setInterval(function(){ 
    me.cycle(); 
    },this.delay); 
} 

或者只是使用箭頭功能

this.start = function(){ 
    this.interval = setInterval(() => this.cycle(), this.delay); 
}