Question

我正在尝试使用对象制作一个基于JavaScript的基本计算器。由于某种原因，属性“ calculator.divide”似乎返回了两个数字。

我已经在在线编译器（js.do＆code.sololearn.com）和记事本中尝试过此操作，但是它似乎不起作用。

var n1 = +(prompt("Enter 1st number:"));
var n2 = +(prompt("Enter 2nd number:"));
//gets user input & declares variables
//+ for changing string to integer
var calculator = {
 add: (n1 + n2), subtract: (n1 - n2), multiply: (n1 * n2), divide: (n1 / n2)
};
var operation = prompt("enter an operation: add, subtract, multiply, or divide");
if (operation = "add") {
    document.write(calculator.add);
}
else if (operation = "subtract") {
    document.write(calculator.subtract);
}
 else if (operation = "multiply") {
    document.write(calculator.multiply);
}
 else if (operation = "divide") {
    document.write(calculator.divide);
}

例如，如果我输入6作为我的第一个数字，输入2作为我的第二个数字，据我了解，当访问“ calculator.divide”时，它将输出“ 3”。似乎并非如此。相反，它输出“ 8”，就好像要添加它们一样。

Answer 1

(operation = "add")是错误的，它必须是(operation === "add")。其余if都一样。而不是进行比较，它只是分配值

var n1 = +(prompt("Enter 1st number:"));
var n2 = +(prompt("Enter 2nd number:"));
//gets user input & declares variables
//+ for changing string to integer
var calculator = {
  add: (n1 + n2),
  subtract: (n1 - n2),
  multiply: (n1 * n2),
  divide: (n1 / n2)
};
var operation = prompt("enter an operation: add, subtract, multiply, or divide");
if (operation === "add") {
  document.write(calculator.add);
} else if (operation === "subtract") {
  document.write(calculator.subtract);
} else if (operation === "multiply") {
  document.write(calculator.multiply);
} else if (operation === "divide") {
  document.write(calculator.divide);
}

您可以避免if-else并使用对象查找

var n1 = +(prompt("Enter 1st number:"));
var n2 = +(prompt("Enter 2nd number:"));
var operation = prompt("enter an operation: add, subtract, multiply, or divide");

function execute(n1, n2, ops) {
  calculator = {
    add: (n1 + n2),
    subtract: (n1 - n2),
    multiply: (n1 * n2),
    divide: (n1 / n2),
  }
  return (calculator[ops]);

}
document.write(execute(n1, n2, operation.trim()))

您还可以避免使用内部计算功能

var n1 = +(prompt("Enter 1st number:"));
var n2 = +(prompt("Enter 2nd number:"));
var operation = prompt("enter an operation: add, subtract, multiply, or divide");

function calculator(n1, n2, ops) {
  return {
    add: (n1 + n2),
    subtract: (n1 - n2),
    multiply: (n1 * n2),
    divide: (n1 / n2),
  }[ops];

}
document.write(calculator(n1, n2, operation.trim()))

Javascript将除法（/）检测为加法（+）

1 个答案: