Question

我试图检查两个数组是否相同，但不适用于长度为1的数组！

控制台输出预期为

true
false
true
false

var test1 = [0,1,2];
var test2 = [0,1,2];
console.log(test1.toString() == test2.toString());
console.log(test1.toString() == !test2.toString());

test1 = [0];
test2 = [0];
console.log(test1.toString() == test2.toString());
console.log(test1.toString() == !test2.toString());

Answer 1

因为最后一个被评估为：

 [0].toString() == ![0].toString()
 "0" == !"0"
 "0" == !true
 "0" == false
 0 == false
 false == false
 true

TLDR：不要试图通过对它们进行字符串化来比较它们，这总是会导致一些意想不到的副作用。

Answer 2

要测试某项是否“不相等”，请使用x != y或x !== y而不是x == !y：

var test1 = [0,1,2];
var test2 = [0,1,2];
console.log(test1.toString() == test2.toString());
console.log(test1.toString() != test2.toString());

test1 = [0];
test2 = [0];
console.log(test1.toString() == test2.toString());
console.log(test1.toString() != test2.toString());

// third test to make sure we see that different arrays are different
test1 = [0];
test2 = [0, 1];
console.log(test1.toString() == test2.toString());
console.log(test1.toString() != test2.toString());

// another kind of different
test1 = [0];
test2 = [1];
console.log(test1.toString() == test2.toString());
console.log(test1.toString() != test2.toString());

但是，将数组转换为字符串以确定它们是否等效，尽管它可以处理数字数组，但通常情况下不起作用。您需要比较长度，如果长度相同，则可以使用every来检查元素。像这样：

function arrayEqual(a, b) {
  return a.length === b.length &&
         a.every((v, i) => v == b[i]);
}

var test1 = [0,1,2];
var test2 = [0,1,2];
console.log(arrayEqual(test1, test2));
console.log(!arrayEqual(test1, test2));

test1 = [0];
test2 = [0];
console.log(arrayEqual(test1, test2));
console.log(!arrayEqual(test1, test2));

// third test to make sure we see that different arrays are different
test1 = [0];
test2 = [0, 1];
console.log(arrayEqual(test1, test2));
console.log(!arrayEqual(test1, test2));

// another kind of different
test1 = [0];
test2 = [1];
console.log(arrayEqual(test1, test2));
console.log(!arrayEqual(test1, test2));

Answer 3

您可以使用严格比较（===和!==）来工作，并跳过!布尔否定运算符的使用，该运算符会将字符串强制为布尔值。您可以查看coercion以获得更多信息。

var test1 = [0,1,2];
var test2 = [0,1,2];
console.log(test1.toString() === test2.toString());
console.log(test1.toString() !== test2.toString());

test1 = [0];
test2 = [0];
console.log(test1.toString() === test2.toString());
console.log(test1.toString() !== test2.toString());

但是，这种方法不适用于所有情况，例如：

var test1 = [""];
var test2 = [null];
console.log(test1.toString() === test2.toString());
console.log(test1.toString() !== test2.toString());

最好使用类似Array.every()方法的东西：

var test1 = [""];
var test2 = [null];
var test3 = [1,2,3,4];
var test4 = [1,2,3,4];

const compareArray = (a1, a2) =>
{
    return a1.length === a2.length && a1.every((val, idx) => val === a2[idx]);
}

console.log(compareArray(test1, test2));
console.log(compareArray(test3, test4));

Answer 4

您可以尝试这种方法吗？

var test1 = [0,1,2];
var test2 = [0,1,2];
console.log(test1.every((item, i) => test2[i] === item));
console.log(!test1.every((item, i) => test2[i] === item));

test1 = [0];
test2 = [0];
console.log(test1.every((item, i) => test2[i] === item));
console.log(!test1.every((item, i) => test2[i] === item));

我确定它会起作用。希望对您有帮助，祝您有美好的一天。

检查数组是否相同有时无法正常工作？

4 个答案: