if (action === 'number') { if(firstNum === undefined){ display.textContent = buttonContent firstNum = buttonContent }else{ display.textContent = display.textContent + buttonContent } lastNum = display.textContent } if (action === 'operator') { firstNum = undefined dotNum = undefined previousNum = display.textContent operatorForAdvanced = buttonContent } if (action === 'decimal') { if(dotNum === undefined){ if(firstNum === undefined){ display.textContent = '0' + buttonContent }else{ display.textContent = display.textContent + buttonContent } firstNum = buttonContent dotNum = buttonContent } } if (action === 'clear') { display.textContent = '0' firstNum = undefined operatorForAdvanced = undefined previousNum = undefined lastNum = undefined dotNum = undefined } if (action === 'calculate') { preCalculate = buttonContent if(operatorForAdvanced !== undefined){ dotNum = undefined if(previousNum !== undefined){ display.textContent = calculate(previousNum, operatorForAdvanced, lastNum) previousNum = undefined }else{ display.textContent = calculate(display.textContent, operatorForAdvanced, lastNum) } } }