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
Undefined means that a variable has been declared, but the value of that variable has not yet been defined. In JavaScript, there are Undefined (type), undefined (value) and undefined (variable).
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). This error occurs when we want to access a property on a variable whose value is undefined or null.
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 addmethod
- Cannot read property each
- Cannot read property bind
- Cannot read property data
- Cannot read property helpers
- Cannot read property datatable
- Cannot read property json
- Cannot read property scrolltop
- Cannot read property extend
- Cannot read property style
- Cannot read property zoneid
- Cannot read property jspdf
- Cannot read property option
- Cannot read property name
- Cannot read property words
- Cannot read property html
- Cannot read property key
- Cannot read property createelement
- Cannot read property history
- Cannot read property focus
- Cannot read property getcontext
- Cannot read property classname
- Cannot read property constructor
- Cannot read property touppercase
- Cannot read property register
- Cannot read property xe
- Cannot read property value
- Cannot read property init
- Cannot read property error
- Cannot read property form
- Cannot read property getitem
- Cannot read property textcontent
- Cannot read property type
- Cannot read property editor
- Cannot read property left
- Cannot read property websiteid
- Cannot read property keyboard
- Cannot read property firstchild
- Cannot read property msie
- Cannot read property getelementsbytagname
- Cannot read property indexof
- Cannot read property preventdefault
- Cannot read property xhr
- Cannot read property map
- Cannot read property play
- Cannot read property install
- Cannot read property zindex
- Cannot read property tostring
- Cannot read property mouse
- Cannot read property innerhtml
- Cannot read property target
- Cannot read property addeventlistener
- Cannot read property rows
- Cannot read property id
- Cannot read property getters
- Cannot read property split
- Cannot read property width