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JavaScript

Posted by brandonlind2
brandonlind2
7,823 Points

Does anyone know why this method is returning NaN? 

let count= {
    amount: 0,
    count: function(){
            this.amount++
            console.log(this.amount);
              },
    start: function(num){         
        setInterval(this.count,num)
        }
    }

if i were to run count.start(500); it would return not a number

1 Answer

Thomas Nilsen
Thomas Nilsen
14,957 Points

Because

start: function(num){         
        setInterval(this.count,num)
        }

the keyword 'this' inside setinterval is no longer pointing to your object, but the window-object.

One option would be to use the bind function like this

let count= {
    amount: 0,
    count: function(){
            this.amount++
            console.log(this.amount);
              },
    start: function(num){         
        setInterval(this.count.bind(this),num)
        }
    }

     count.start(500);
brandonlind2
brandonlind2
7,823 Points

thanks!!