The main problem is that if you just check typeof(object) == "object" , it will return true if object is null since null 's type is "object" . ... <看更多>

Javascript null is a primitive type that has one value null. · JavaScript uses the null value to represent a missing object. · Use the strict equality operator ( ... ... <看更多>

const object = { " key ": " value " }. console.log(typeof object) // "object". console.log(object !== null) // true. console.log(object != null) // true. ... <看更多>

The developer who wrote the code did not anticipate that the object could be null so he did not include any checks, and when the page was loaded ... ... <看更多>