First-Calculator/script.js at main · rafinahmed7/First-Calculator · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
document.addEventListener('DOMContentLoaded', () => {
    const previousOperandElement = document.querySelector('.previous-operand');
    const currentOperandElement = document.querySelector('.current-operand');
    const buttons = document.querySelectorAll('button');

    let currentOperand = '0';
    let previousOperand = '';
    let operation = undefined;
    let shouldResetScreen = false;

    function clear() {
        currentOperand = '0';
        previousOperand = '';
        operation = undefined;
        updateDisplay();
    }

    function deleteNumber() {
        if (currentOperand === '0') return;
        if (currentOperand.length === 1) {
            currentOperand = '0';
        } else {
            currentOperand = currentOperand.slice(0, -1);
        }
        updateDisplay();
    }

    function appendNumber(number) {
        if (shouldResetScreen) {
            currentOperand = '';
            shouldResetScreen = false;
        }
        if (number === '.' && currentOperand.includes('.')) return;
        if (currentOperand === '0' && number !== '.') {
            currentOperand = number;
        } else {
            currentOperand += number;
        }
        updateDisplay();
    }

    function chooseOperation(op) {
        if (currentOperand === '') return;
        if (previousOperand !== '') {
            compute();
        }
        operation = op;
        previousOperand = currentOperand;
        currentOperand = '0';
        updateDisplay();
    }

    function compute() {
        let computation;
        const prev = parseFloat(previousOperand);
        const current = parseFloat(currentOperand);
        if (isNaN(prev) || isNaN(current)) return;

        switch (operation) {
            case '+':
                computation = prev + current;
                break;
            case '-':
                computation = prev - current;
                break;
            case '×':
                computation = prev * current;
                break;
            case '÷':
                if (current === 0) {
                    alert('Cannot divide by zero!');
                    return;
                }
                computation = prev / current;
                break;
            default:
                return;
        }

        currentOperand = computation.toString();
        operation = undefined;
        previousOperand = '';
        shouldResetScreen = true;
        updateDisplay();
    }

    function getDisplayNumber(number) {
        const stringNumber = number.toString();
        const integerDigits = parseFloat(stringNumber.split('.')[0]);
        const decimalDigits = stringNumber.split('.')[1];
        let integerDisplay;

        if (isNaN(integerDigits)) {
            integerDisplay = '';
        } else {
            integerDisplay = integerDigits.toLocaleString('en', {
                maximumFractionDigits: 0
            });
        }

        if (decimalDigits != null) {
            return `${integerDisplay}.${decimalDigits}`;
        } else {
            return integerDisplay;
        }
    }

    function updateDisplay() {
        currentOperandElement.textContent = getDisplayNumber(currentOperand);
        if (operation != null) {
            previousOperandElement.textContent =
                `${getDisplayNumber(previousOperand)} ${operation}`;
        } else {
            previousOperandElement.textContent = '';
        }
    }

    // Add click event listeners to all buttons
    buttons.forEach(button => {
        button.addEventListener('click', () => {
            if (button.classList.contains('special')) {
                if (button.textContent === 'AC') {
                    clear();
                } else if (button.textContent === 'DEL') {
                    deleteNumber();
                }
            } else if (button.classList.contains('operator')) {
                if (button.textContent === '=') {
                    compute();
                } else {
                    chooseOperation(button.textContent);
                }
            } else {
                appendNumber(button.textContent);
            }
        });
    });

    // Initialize display
    updateDisplay();
});