File size: 3,060 Bytes
1e92f2d |
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 |
import Big from "big.js";
import operate from "./operate";
import isNumber from "./isNumber";
/**
* Given a button name and a calculator data object, return an updated
* calculator data object.
*
* Calculator data object contains:
* total:String the running total
* next:String the next number to be operated on with the total
* operation:String +, -, etc.
*/
export default function calculate(obj, buttonName) {
if (buttonName === "AC") {
return {
total: null,
next: null,
operation: null,
};
}
if (isNumber(buttonName)) {
if (buttonName === "0" && obj.next === "0") {
return {};
}
// If there is an operation, update next
if (obj.operation) {
if (obj.next) {
return { next: obj.next + buttonName };
}
return { next: buttonName };
}
// If there is no operation, update next and clear the value
if (obj.next) {
const next = obj.next === "0" ? buttonName : obj.next + buttonName;
return {
next,
total: null,
};
}
return {
next: buttonName,
total: null,
};
}
if (buttonName === "%") {
if (obj.operation && obj.next) {
const result = operate(obj.total, obj.next, obj.operation);
return {
total: Big(result)
.div(Big("100"))
.toString(),
next: null,
operation: null,
};
}
if (obj.next) {
return {
next: Big(obj.next)
.div(Big("100"))
.toString(),
};
}
return {};
}
if (buttonName === ".") {
if (obj.next) {
// ignore a . if the next number already has one
if (obj.next.includes(".")) {
return {};
}
return { next: obj.next + "." };
}
return { next: "0." };
}
if (buttonName === "=") {
if (obj.next && obj.operation) {
return {
total: operate(obj.total, obj.next, obj.operation),
next: null,
operation: null,
};
} else {
// '=' with no operation, nothing to do
return {};
}
}
if (buttonName === "+/-") {
if (obj.next) {
return { next: (-1 * parseFloat(obj.next)).toString() };
}
if (obj.total) {
return { total: (-1 * parseFloat(obj.total)).toString() };
}
return {};
}
// Button must be an operation
// When the user presses an operation button without having entered
// a number first, do nothing.
// if (!obj.next && !obj.total) {
// return {};
// }
// User pressed an operation button and there is an existing operation
if (obj.operation) {
return {
total: operate(obj.total, obj.next, obj.operation),
next: null,
operation: buttonName,
};
}
// no operation yet, but the user typed one
// The user hasn't typed a number yet, just save the operation
if (!obj.next) {
return { operation: buttonName };
}
// save the operation and shift 'next' into 'total'
return {
total: obj.next,
next: null,
operation: buttonName,
};
}
|