Why doesn't the addition work with my method in Javascript ???

Question

I tried to make a program to add two numbers in the same string together.
With some strings like "2+3" it works, but with the string"100123+456" it outputs NaN.

Here is the program :

var addition = "1+12"
var num1= parseInt(addition);
var Length = num1.length ;
var half=addition .substr(num1,Length);
var num2 = parseInt (half);
var solution = num1+num2;
alert(solution);

Please help

Answer 1

Darko _007 Take a look at the code here for options.

https://code.sololearn.com/WAkXK6YeTeqD/?ref=app

[UPDATE:]
Basically, you can use the following:

let expression = "100123+456";
let operands = expression.match(/^(\d+)\+(\d+)$/);

let operandA= parseInt(operands[1]);
let operandB = parseInt(operands[2]);

console.log(operandA+operandB);

Answer 2

The problem is "+" cant be parsed in your string the string should contain digits but allows plus or minus at the beginning of the string, doing "-200" is ok this will parse giving you -200 as an integer.

Answer 3

I'd use RegEx for this. I can post a solution when I get a free chance. In the meantime, do some research and give it a go.

Answer 4

Darko _007 I've updated my original answer with the minimum code to do the job.

Answer 5

var len = num1.toString().length;

var half = addition.substr(len);

Answer 6

David Carroll I don't know what RegEx is and I am not able to understand your whole Code (I am a beginner so don't kill me), but I saw in your solution that I can use "eval" to calculate an addition in a string.