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 reload
- Cannot read property preventdefault
- Cannot read property split
- Cannot read property filter
- Cannot read property display
- Cannot read property getelementsbyclassname
- Cannot read property jsonmodel
- Cannot read property nodename
- Cannot read property add
- Cannot read property prototype
- Cannot read property appendchild
- Cannot read property hide
- Cannot read property location
- Cannot read property history
- Cannot read property getcontext
- Cannot read property option
- Cannot read property removechild
- Cannot read property locals
- Cannot read property y
- Cannot read property add
- Cannot read property zindex
- Cannot read property ngmodule
- Cannot read property classname
- Cannot read property nodetype
- Cannot read property toggle
- Cannot read property view
- Cannot read property mouse
- Cannot read property contains
- Cannot read property json
- Cannot read property data
- Cannot read property version
- Cannot read property value
- Cannot read property props
- Cannot read property xhr
- Cannot read property browser
- Cannot read property each
- Cannot read property fn
- Cannot read property jspdf
- Cannot read property innerhtml
- Cannot read property zoneid
- Cannot read property play
- Cannot read property zone
- Cannot read property adatasort
- Cannot read property join
- Cannot read property webkit
- Cannot read property query
- Cannot read property uid
- Cannot read property left
- Cannot read property helpers
- Cannot read property getelementsbytagname
- Cannot read property find
- Cannot read property hasownproperty
- Cannot read property 3
- Cannot read property style
- Cannot read property submit
- Cannot read property tolowercase
- Cannot read property validate