如何检查object内数组是否为空JavaScript

var obj = {
  array: [1, 2, 3]
};

if (obj.array.length === 0) {
  console.log("数组为空");
} else {
  console.log("数组不为空");
}

var obj = {
  array: []
};

if (obj.array.every(function(item) { return !item; })) {
  console.log("数组为空");
} else {
  console.log("数组不为空");
}

var obj = {
  array: undefined
};

if (typeof obj.array === "undefined" || obj.array === null) {
  console.log("数组为空");
} else {
  console.log("数组不为空");
}