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 find
- Cannot read property bind
- Cannot read property nodetype
- Cannot read property init
- Cannot read property set
- Cannot read property xrm
- Cannot read property locals
- Cannot read property addeventlistener
- Cannot read property element
- Cannot read property name
- Cannot read property fn
- Cannot read property rows
- Cannot read property classlist
- Cannot read property left
- Cannot read property jspdf
- Cannot read property split
- Cannot read property json
- Cannot read property jsonmodel
- Cannot read property jquery
- Cannot read property location
- Cannot read property indexof
- Cannot read property webkit
- Cannot read property hide
- Cannot read property nodename
- Cannot read property queryselector
- Cannot read property getters
- Cannot read property write
- Cannot read property append
- Cannot read property emit
- Cannot read property x
- Cannot read property document
- Cannot read property data
- Cannot read property readtext
- Cannot read property height
- Cannot read property hasattribute
- Cannot read property quesryselectorall
- Cannot read property have
- Cannot read property dataset
- Cannot read property keyboard
- Cannot read property then
- Cannot read property getattribute
- Cannot read property extend
- Cannot read property queuedepthsort
- Cannot read property header
- Cannot read property 3
- Cannot read property foreach
- Cannot read property html
- Cannot read property websiteid
- Cannot read property keycode
- Cannot read property version
- Cannot read property getcontext
- Cannot read property ext
- Cannot read property value
- Cannot read property visible
- Cannot read property getelementsbyclassname
- Cannot read property getelementsbytagname
- Cannot read property uid