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 init
- Cannot read property replace
- Cannot read property addeventlistener
- Cannot read property data
- Cannot read property classlist
- Cannot read property innerhtml
- Cannot read property add
- Cannot read property uid
- Cannot read property touppercase
- Cannot read property find
- Cannot read property left
- Cannot read property prototype
- Cannot read property findindex
- Cannot read property hasattribute
- Cannot read property json
- Cannot read property rows
- Cannot read property element
- Cannot read property queuedepthsort
- Cannot read property error
- Cannot read property which
- Cannot read property append
- Cannot read property y
- Cannot read property view
- Cannot read property slice
- Cannot read property browser
- Cannot read property foreach
- Cannot read property use
- Cannot read property browserwindow
- Cannot read property zone
- Cannot read property ext
- Cannot read property then
- Cannot read property validate
- Cannot read property call
- Cannot read property style
- Cannot read property xhr
- Cannot read property trim
- Cannot read property jquery
- Cannot read property submit
- Cannot read property constructor
- Cannot read property destroy
- Cannot read property adatasort
- Cannot read property history
- Cannot read property map
- Cannot read property appendchild
- Cannot read property words
- Cannot read property form
- Cannot read property reload
- Cannot read property push
- Cannot read property includes
- Cannot read property bind
- Cannot read property xe
- Cannot read property editor
- Cannot read property install
- Cannot read property keyup
- Cannot read property getelementsbyclassname
- Cannot read property ngmodule
- Cannot read property pending