cannot increment a localStorage value

Question

I am trying to increment my localStorage value every time a condition in if statement is true but it seems I am not able to do it right. Tried everything possible. Here is my code that does the check and increments the value.

for(var j = 0; j < inputArray.length; j++){
    for(var k = 0; k < this.probsSolved.length; k++){
        if(inputArray[k] == this.probsSolved[j] ){

            //increment the localStorage value here

            **this.storage.set(probSolKey,parseInt(this.storage.get(probSolKey)) + 1);**

            if(this.storage.get(probSolKey) >= totalProbToSolve){
                this.storage.set(achkey,1);
                this.triggerAchievements(id,name);
                return;
            }
        }
    }
}

So I have a localStorage plugin for ImpactJS engine which I am using. I am trying to increment probSolKey which I pass in my function as a parameter String. Whenever the condition is met I try to increment itself by 1. I don't know how to implement this correctly. Anyone help me out on this, will really appreciate it!

Doing some debugging i found out this:

console.log(this.storage.get(probSolKey));

Throws a weird value of "NaN".

Answer 1

When you stored the value of the property you're trying to increment, you thought you stored a number, but you actually didn't.

You stored a value that was suposed to be a number so it was converted to one, but the conversion failed because the value couldn't be parsed as a number.

That's what NaN stands for, Not a Number, something that couldn't be parsed as a number.