var b = 2；

var c = a+b；

In this way, the solution of c is12;

Using the Number () function can solve this problem, as follows?

Var c = number (a)+number (b);

In this way, the solution of c is 3.

Extended data

The value of the JavaScript Number () function object is converted to a number.

& ltscript type = " text/JavaScript " & gt；

Var test 1= new Boolean (true);

var test 2 = new Boolean(false)；

var test3 = new Date()；

Var test4= new string ("999");

Var test5= new string ("999888");

document . write(Number(test 1)+" & lt； br />);

document . write(Number(test2)+" & lt； br />);

document . write(Number(test3)+" & lt； br />);

document . write(Number(test4)+" & lt； br />);

document . write(Number(test5)+" & lt； br />);

& lt/script & gt；