Calculator: How do I get the result of the equations?

Question

The numbers are displaying on the screen. Now how might I create a 'getResult' function that works when you click the equal button to actually return the result from each equation from my operate() function? Right now, when you click the equal sign the last number remains on the display screen and nothing happens.

const NUMBERS = document.querySelectorAll('.number-btn');
const equal=document.querySelector('.equalbtn');
const clear=document.querySelector('.clearbtn');
const operator=document.querySelectorAll('.operator')

let a;
let b;
let result;
let operand;


  
let aIsCurrent = true;
let operandIsPressed = false;

function add(a, b) {
    return (a + b).toFixed(2);
  }
  function substract(a, b) {
    return (a - b).toFixed(2);
  }
  function multiply(a, b) {
    return (a * b).toFixed(2);
  }
  function divide(a, b) {
    return (a / b).toFixed(2);
  }
  
  function operate(a, b, operator) {
    switch (operator) {
      case 'sum':
        result= add(a, b);
        break;
      case 'subtract':
        result= substract(a, b);
        break;
      case 'multiply':
        result= multiply(a, b);
        break;
      case 'divide':
        result= divide(a, b);
        break;
      
    }
  };
  
  function insertToDisplay(value) {
    if (operandIsPressed) {
      DISPLAY.textContent = value;
      operandIsPressed = false;
    } else {
      DISPLAY.textContent += value;
    }
  }
  
  function storeOperand(value) {
    operandIsPressed = true;
    if (result !== undefined) {
      a = result;
      result = undefined;
    } else if (aIsCurrent) {
      a = Number(DISPLAY.textContent);
      aIsCurrent = false;
    } else {
      b = Number(DISPLAY.textContent);
      result = operate(a, b, operator);
      a = b = undefined;
      DISPLAY.textContent = resultNumber;
    }
    operand = value;
  }
  
  function getResult(){
     
     };

  function clearDisplay () {
      DISPLAY.textContent='';
      return;
  };
  

//event listeners
NUMBERS.forEach((button) => {
button.addEventListener('click', (e) => insertToDisplay(button.value));
  });
  
clear.addEventListener('click', clearDisplay);

operator.forEach((button) => {
 button.addEventListener('click', (e) => storeOperand(button.value));
});

equal.addEventListener('click', getResult);

@Fakt309 Hey, yeah I know. I've tried a few things to no avail so I left it empty for now -was hoping for any suggestions — toocoolforschool97, Apr 03 '21 at 23:37
Can you create a snippet? Edit the question and click the `<>` button — Christian Vincenzo Traina, Apr 03 '21 at 23:52
Does this answer your question? [How to evaluate an infix expression in just one scan using stacks?](https://stackoverflow.com/questions/13421424/how-to-evaluate-an-infix-expression-in-just-one-scan-using-stacks) — Tangentially Perpendicular, Apr 03 '21 at 23:57

score 0 · Answer 1 · answered Apr 03 '21 at 23:42

0

You can use math.js library

<script src="https://cdnjs.cloudflare.com/ajax/libs/mathjs/9.3.0/math.js"></script>
<script>
  function getResult(){
    insertToDisplay(math.evaluate(DISPLAY.textContent));
  };
</script>

answered Apr 03 '21 at 23:42

Fakt309

821
5
14

thank you, unfortunately I would but its a project for The Odin Project and we're encouraged to try and find a solution with Vanilla javascript – toocoolforschool97 Apr 03 '21 at 23:44

Calculator: How do I get the result of the equations?

1 Answers1