Question 51854 in Javascript Question posted in
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JS doesn't update variable value and outputs old result – Javascript

I updated the value of the variable val1, but the value 5 is still displayed in the console.

let val1 = 2
let val2 = 3
let sum = val1 + val2
console.log(sum) // 5
val1 = 3
console.log(sum) // 5

After changing the value of val1, I expected to see the updated value of the sum equal to = 6. But its old value of the sum was displayed. Why hasn’t the value been updated?

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3

Answers


  1. 0

    You are printing the sum which has been already taken the value. So if you really want to updated sum of value val1 you could write your code like this.

    let val1 = 2
let val2 = 3
let sum = val1 + val2
console.log(sum) // 5
val1 = 3
console.log(val1+val2) // 6
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  2. 0

    You change the values but you don’t update the sum!

    Method 1 :

    let val1 = 2
let val2 = 3
let sum = val1 + val2 // do the sum of the values
console.log(sum) // 5
val1 = 3
sum = val1 + val2 // redo the sum of the updated values
console.log(sum) // 6
// Or just
console.log(val1+val2) // 6

    Method 2 :

    function sumFunction(a,b){
  return (a+b);
}
val1 = 2;
val2 = 3;
console.log(sumFunction(val1,val2)); //output 5
val1 = 3;
val2 = 3;
console.log(sumFunction(val1,val2)); //output 6
console.log(sumFunction(5,8)); // output 13

    Method 2b :

    val1 = 2;
val2 = 3;
console.log(sumFunction(val1,val2)); //output 5
val1 = 3;
val2 = 3;
console.log(sumFunction(val1,val2)); //output 6
console.log(sumFunction(5,8)); // output 13
function sumFunction(a,b){
   return (a+b);
}

    Method 3 (as Konrad suggest a function too):

    val1 = 4;
val2 = 5;
let sumArrowFunction = (a,b) => a + b;
console.log(sumArrowFunction(val1,val2));
console.log(sumArrowFunction(5,5));

    Alternative method to be complete:
    Here you display the full operation…

    val1 = 2;
val2 = 1;
console.log(calcFunction(val1,val2));
console.log(calcFunction(12,3));
function calcFunction(a,b){
   return (`${a}  + ${b}  =  ${a+b}`);
}
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  3. 0

    You can use a function

    let val1 = 2
let val2 = 3
let sum = () => val1 + val2
console.log(sum()) // 5
val1 = 3
console.log(sum()) // 6
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