Question

I have a question understanding some JavaScript syntax, below:

var myObject = {
    value: 0;
    increment: function (inc) {
        this.value += typeof inc === 'number' ? inc : 1;
    }
};
myObject.increment(  );
document.writeln(myObject.value);    // 1
myObject.increment(2);
document.writeln(myObject.value);    // 3

Specifically:

this.value += typeof inc === 'number' ? inc : 1;

Is this line saying that if:

typeof inc === 'number'

then:

this.value += inc

Any good way to think about this or resource to help understand would be appreciated.

Answer 1

That’s correct, it’s called a ternary operator. If the statement resolves to true it does the first option if not it resolves the second. It can be broken down into a simple if/else

if (typeof inc === 'number') this.value += inc;
else this.value++;