Uncaught TypeError: Cannot read property '' of undefined
JavaScript Error: Uncaught TypeError: Cannot read property '' of null
JavaScript TypeError is returned when an operand or argument passed to a function is incompatible with the type expected by that operator or function. This error occurs in the browser when you read a property or call a method on an undefined object.
There are a few variations of this error depending on the property you are trying to access. Sometimes instead of undefined it will output null:
Uncaught TypeError: Cannot read property '' of null
Cannot read property '' of undefined
Cannot read property '' of null
Simply put, undefined means that a variable has been declared but has not yet been given a value. This particular error is probably the easiest to understand from an undefined point of view, because undefined is not considered an object type at all (but its own undefined type instead), and properties cannot belong to only to objects in JavaScript.
This error occurs when we want to access a property on a variable whose value is undefined or null. This error occurs when you try to call a method or try to access a property of a variable that does not exist (is not an object).
Null vs. Undefined in JavaScript The value "undefined" indicates that a variable has been declared, but no value has been assigned. On the other hand, "null" refers to a non-existent object, which basically means "empty" or "nothing". These are two values generally used to indicate the absence of something. Also, undefined and null are two distinct types: undefined is a type itself (undefined) while null is an object.
Other Javascript errors :
- Cannot read property defaultview
- Cannot read property form
- Cannot read property id
- Cannot read property ajax
- Cannot read property quesryselectorall
- Cannot read property replace
- Cannot read property reload
- Cannot read property play
- Cannot read property foreach
- Cannot read property location
- Cannot read property register
- Cannot read property key
- Cannot read property bridge
- Cannot read property display
- Cannot read property history
- Cannot read property 2
- Cannot read property websiteid
- Cannot read property scrolltop
- Cannot read property 3
- Cannot read property append
- Cannot read property getitem
- Cannot read property height
- Cannot read property bind
- Cannot read property ngmodule
- Cannot read property apply
- Cannot read property data
- Cannot read property setstate
- Cannot read property rows
- Cannot read property filter
- Cannot read property html
- Cannot read property then
- Cannot read property visible
- Cannot read property destroy
- Cannot read property error
- Cannot read property dataset
- Cannot read property type
- Cannot read property validate
- Cannot read property editor
- Cannot read property createdocumentfragment
- Cannot read property render
- Cannot read property zone
- Cannot read property document
- Cannot read property getcontext
- Cannot read property contains
- Cannot read property async
- Cannot read property readtext
- Cannot read property bind
- Cannot read property msie
- Cannot read property each
- Cannot read property remove
- Cannot read property length
- Cannot read property set
- Cannot read property keyboard
- Cannot read property xlsx
- Cannot read property xhr
- Cannot read property call
- Cannot read property ext