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 ngmodule
- Cannot read property write
- Cannot read property hasattribute
- Cannot read property remove
- Cannot read property filter
- Cannot read property tostring
- Cannot read property includes
- Cannot read property join
- Cannot read property value
- Cannot read property length
- Cannot read property msie
- Cannot read property readtext
- Cannot read property setattribute
- Cannot read property html
- Cannot read property findindex
- Cannot read property getters
- Cannot read property toggle
- Cannot read property target
- Cannot read property 3
- Cannot read property defaultview
- Cannot read property getcontext
- Cannot read property queuedepthsort
- Cannot read property getelementsbytagname
- Cannot read property replace
- Cannot read property key
- Cannot read property reload
- Cannot read property helpers
- Cannot read property nodetype
- Cannot read property reset
- Cannot read property bridge
- Cannot read property dataset
- Cannot read property scrolltop
- Cannot read property getelementsbyclassname
- Cannot read property play
- Cannot read property focus
- Cannot read property indexof
- Cannot read property jspdf
- Cannot read property datatable
- Cannot read property set
- Cannot read property split
- Cannot read property words
- Cannot read property xrm
- Cannot read property props
- Cannot read property textcontent
- Cannot read property map
- Cannot read property add
- Cannot read property zindex
- Cannot read property mouse
- Cannot read property slice
- Cannot read property state
- Cannot read property createdocumentfragment
- Cannot read property validate
- Cannot read property rows
- Cannot read property createelement
- Cannot read property play
- Cannot read property browser
- Cannot read property ext