Explain The function Of this Sign Code (Js)

1

Sorry,I new in JavaScript and have a problem to understand this code

const calculator = {
    displayNumber : '0',
    operator : null,
    firstNumber : null,
    waitingForSecondNumber : false
};

function updateDisplay() {
    document.querySelector("#displayNumber").innerText = calculator.displayNumber;
}

function clearCalculator() {
    calculator.displayNumber = '0';
    calculator.operator = null;
    calculator.firstNumber = null;
    calculator.waitingForSecondNumber = false;
}

function inputDigit(digit) {
    if (calculator.displayNumber === "0"){
        calculator.displayNumber = digit;
    }
    else{
        calculator.displayNumber += digit;
    }
 }

 **const buttons = document.querySelectorAll(".button");**
** for (let button of buttons) {**
**    button.addEventListener('click', function(event) {**

**        const target = event.target;**

**        inputDigit(target.innerText);**
**        updateDisplay()**
**    });**
** }**
3

@camperextraordinaire yes, I already gave it with this sign (*)

5 
const buttons = document.querySelectorAll(".button");
// there is a class in your html file called 'button' and we use the DOM to assign its reference to a variable called 'buttons' in this file
//  querySelectorAll will return all class references inside an array [] called 'buttons'
// now we loop  through the buttons array
for (let button of buttons) {
    // for every item in the buttons array we add an event listener
    button.addEventListener('click', function(event) { // this function will run when the button is clicked
        const target = event.target;
        inputDigit(target.innerText);
        updateDisplay()**
    });
}
1 Like
6

Terimakasih atas penjelasannya,tapi apa fungsi dari “const target = event.target”

7
  1. mdn: addEventListener
  2. event types
function(event){
        // addEventListener returns an object called event that we use in our function
       // event has a key called 'target that refers to your button item'
        const target = event.target;         
        // we just shorten event.target to 'target' so that its easier to read and type
        inputDigit(target.innerText); // we run target.innerText through the function that was made earlier in yout code
        updateDisplay()
}
1 Like