js 判断对象存在某个值

可以使用 `Object.values()` 方法获取对象的所有属性值，然后使用 `Array.includes()` 方法判断指定的值是否在这些属性值中。示例如下：

const obj = { name: 'John', age: 25, gender: 'male' };
if (Object.values(obj).includes('male')) {
  console.log('obj has male value');
}
if (Object.values(obj).includes('female')) {
  console.log('obj has female value');
} else {
  console.log('obj does not have female value');
}

输出结果为：

obj has male value
obj does not have female value

另外，如果要检查某个属性值是否等于指定的值，可以直接使用 `===` 运算符进行比较。示例如下：

const obj = { name: 'John', age: 25, gender: 'male' };
if (obj.gender === 'male') {
  console.log('obj has male gender');
}
if (obj.gender === 'female') {
  console.log('obj has female gender');
} else {
  console.log('obj does not have female gender');
}

输出结果与上面的示例相同。