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jimmitt/calculator.htm

Created August 3, 2020 03:35
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Calculator
Raw
calculator.htm
<html>
<head>
<title>Calculator</title>
</head>
<body>
<table width="100px" style="text-align: center; vertical-align: middle;" border="2px">
<tr>
<td colSpan="4"><input type="text" id="display" style="width: 110px;" disabled/></td>
</tr>
<tr>
<td><button type="button" id="btn7" onClick="btnDigit(7);">7</button></td>
<td><button type="button" id="btn8" onClick="btnDigit(8);">8</button></td>
<td><button type="button" id="btn9" onClick="btnDigit(9);">9</button></td>
<td><button type="button" id="btnDivide" onClick="btnDivide();">/</button></td>
</tr>
<tr>
<td><button type="button" id="btn4" onClick="btnDigit(4);">4</button></td>
<td><button type="button" id="btn5" onClick="btnDigit(5);">5</button></td>
<td><button type="button" id="btn6" onClick="btnDigit(6);">6</button></td>
<td><button type="button" id="btnMultiply" onClick="btnMultiply();">*</button></td>
</tr>
<tr>
<td><button type="button" id="btn1" onClick="btnDigit(1);">1</button></td>
<td><button type="button" id="btn2" onClick="btnDigit(2);">2</button></td>
<td><button type="button" id="btn3" onClick="btnDigit(3);">3</button></td>
<td><button type="button" id="btnSubtract" onClick="btnSubtract();">-</button></td>
</tr>
<tr>
<td><button type="button" id="btnNegate" onClick="btnNegate();">&plusmn;</button></td>
<td><button type="button" id="btnZero" onClick="btnDigit(0);">0</button></td>
<td><button type="button" id="btnDecimal" onClick="btnDecimal();">.</button></td>
<td><button type="button" id="btnAdd" onClick="btnAdd();">+</button></td>
</tr>
<tr>
<td colSpan="2"><button type="button" id="btnClear" onClick="btnClear();" style="width: 100%;">C</button></td>
<td colSpan="2"><button type="button" id="btnEquals" onClick="btnEquals();" style="width: 100%;">=</button></td>
</tr>
</table>
</body>
</html>
Raw
calculator.js
var prev = 0;
var curr = 0;
var sign = 1;
var display = document.getElementById("display");
var lastOp;
var lastCurr = 0;
function btnDigit(x) {
display.value = display.value+x.toString();
curr = parseFloat(display.value);
}
function btnClear() {
display.value = "";
curr = 0;
prev = 0;
}
function btnAdd() {
prev = prev+curr;
lastOp = btnAdd;
lastCurr = curr;
display.value = "";
curr = 0;
}
function btnSubtract() {
prev = prev-curr;
lastOp = btnSubtract;
lastCurr = curr;
display.value = "";
curr = 0;
}
function btnEquals() {
if (display.value === "") {
curr = lastCurr;
}
lastOp();
display.value = prev.toString();
curr = lastCurr;
}
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