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 pending
- Cannot read property document
- Cannot read property error
- Cannot read property jspdf
- Cannot read property xrm
- Cannot read property query
- Cannot read property tolowercase
- Cannot read property getattribute
- Cannot read property classlist
- Cannot read property getters
- Cannot read property apply
- Cannot read property top
- Cannot read property filter
- Cannot read property header
- Cannot read property get
- Cannot read property call
- Cannot read property document
- Cannot read property add
- Cannot read property readtext
- Cannot read property use
- Cannot read property type
- Cannot read property scrolltop
- Cannot read property match
- Cannot read property key
- Cannot read property form
- Cannot read property 2
- Cannot read property install
- Cannot read property register
- Cannot read property contains
- Cannot read property join
- Cannot read property mouse
- Cannot read property element
- Cannot read property reset
- Cannot read property 3
- Cannot read property write
- Cannot read property click
- Cannot read property view
- Cannot read property validate
- Cannot read property width
- Cannot read property value
- Cannot read property visible
- Cannot read property createelement
- Cannot read property formatdate
- Cannot read property sort
- Cannot read property checked
- Cannot read property render
- Cannot read property zoneid
- Cannot read property firstchild
- Cannot read property parentnode
- Cannot read property target
- Cannot read property name
- Cannot read property map
- Cannot read property addeventlistener
- Cannot read property left
- Cannot read property find
- Cannot read property history
- Cannot read property indexof