Plus Arithmetic Operation

Question

I\'ve tried use Plus Arithmetic Operation to calculate 2 input text type number values, but my result was the values are \"together\", like that:

Answer 1

You need to parse them to an Integer type:

var x = parseInt(plus) + parseInt(plus1);

Then you can use isNaN() to determine whether it was a valid operation or not: (note that I'm checking the value of x not of the resulting output)

if(isNaN(x)){
 result.innerHTML = "?";
}
else{
 result.innerHTML = x;
}

Living demo: http://jsfiddle.net/4KB5Y/3/