jQuery - 获取对象 object 的长度
var bookAuthors = {
"Farmer Giles of Ham": "J.R.R. Tolkien",
"Out of the Silent Planet": "C.S. Lewis",
"The Place of the Lion": "Charles Williams",
"Poetic Diction": "Owen Barfield"
};
// 获取对象的key值
var arr = Object.keys(bookAuthors);
console.log(arr);
// 获取长度
console.log(arr.length);