HTMLTextAreaElement

<textarea> textarea

Baseline: Widely available on the web, in every major browser since Jul 2015, and long enough to count on (since Jan 2018).

niso: Partial 48%. 25 of 52 subtests pass, by system: Linux 48%, macOS 48%. Engines: QuickJS, the engine niso's WPT run uses; Node and Porffor have no recorded run. WPT results recorded at f3b4fa8, 2026-11-10; web-features 3.45.0. WPT tests · niso's support · HTMLTextAreaElement

HTMLTextAreaElement is an interface in idl/html.webidl, inheriting HTMLElement, exposed in Window. What it does is on MDN; this page says what niso has of it.

Status

The web features its members belong to, each with its Baseline status on the web and how much of the feature’s WPT suite passes in niso (see Web platform support).

Feature	On the web	In niso	Members
<textarea>	Widely available	Partial 48% 25 of 52 subtests pass	14

Members

constructor

constructor

[HTMLConstructor] constructor();

form

attribute

readonly attribute HTMLFormElement? form;

int32_t niso_html_text_area_element_get_form(niso_dom* dom, niso_handle self, niso_handle* out);

name

attribute

attribute DOMString name;

int32_t niso_html_text_area_element_get_name(niso_dom* dom, niso_handle self, niso_str* out);
int32_t niso_html_text_area_element_set_name(niso_dom* dom, niso_handle self, const char* value, size_t value_len);

value

attribute

attribute DOMString value;

int32_t niso_html_text_area_element_get_value(niso_dom* dom, niso_handle self, niso_str* out);
int32_t niso_html_text_area_element_set_value(niso_dom* dom, niso_handle self, const char* value, size_t value_len);

defaultValue

attribute

attribute DOMString defaultValue;

int32_t niso_html_text_area_element_get_default_value(niso_dom* dom, niso_handle self, niso_str* out);
int32_t niso_html_text_area_element_set_default_value(niso_dom* dom, niso_handle self, const char* value, size_t value_len);

placeholder

attribute

attribute DOMString placeholder;

int32_t niso_html_text_area_element_get_placeholder(niso_dom* dom, niso_handle self, niso_str* out);
int32_t niso_html_text_area_element_set_placeholder(niso_dom* dom, niso_handle self, const char* value, size_t value_len);

disabled

attribute

attribute boolean disabled;

int32_t niso_html_text_area_element_get_disabled(niso_dom* dom, niso_handle self, bool* out);
int32_t niso_html_text_area_element_set_disabled(niso_dom* dom, niso_handle self, bool value);

readOnly

attribute

attribute boolean readOnly;

int32_t niso_html_text_area_element_get_read_only(niso_dom* dom, niso_handle self, bool* out);
int32_t niso_html_text_area_element_set_read_only(niso_dom* dom, niso_handle self, bool value);

select()

operation

undefined select();

int32_t niso_html_text_area_element_select(niso_dom* dom, niso_handle self);

selectionStart

attribute

[NisoGlue] attribute unsigned long? selectionStart;

selectionEnd

attribute

[NisoGlue] attribute unsigned long? selectionEnd;

selectionDirection

attribute

attribute DOMString? selectionDirection;

int32_t niso_html_text_area_element_get_selection_direction(niso_dom* dom, niso_handle self, niso_str* out);
int32_t niso_html_text_area_element_set_selection_direction(niso_dom* dom, niso_handle self, const char* value, size_t value_len);

setRangeText()

operation

undefined setRangeText(DOMString replacement, optional unsigned long start, optional unsigned long end, optional SelectionMode selectionMode = "preserve");

int32_t niso_html_text_area_element_set_range_text(niso_dom* dom, niso_handle self, const char* replacement, size_t replacement_len, bool has_start, uint32_t start, bool has_end, uint32_t end, const char* selection_mode, size_t selection_mode_len);

setSelectionRange()

operation

undefined setSelectionRange(unsigned long start, unsigned long end, optional DOMString direction);

int32_t niso_html_text_area_element_set_selection_range(niso_dom* dom, niso_handle self, uint32_t start, uint32_t end, const char* direction, size_t direction_len);

selectionOffset()

operation not in JS

[NisoInternal] long selectionOffset(boolean end);

int32_t niso_html_text_area_element_selection_offset(niso_dom* dom, niso_handle self, bool end, int32_t* out);

selectionStart and selectionEnd (unsigned long?) in the glue: the selection’s start, or with end its end, or -1 where they do not apply.

setSelectionOffset()

operation not in JS

[NisoInternal] undefined setSelectionOffset(boolean end, unsigned long offset);

int32_t niso_html_text_area_element_set_selection_offset(niso_dom* dom, niso_handle self, bool end, uint32_t offset);

Not in niso yet

Members the web has, by the BCD keys web-features 3.45.0 lists, that idl/ doesn’t declare. The list is partial: web-features lists only the keys it maps to a feature.

• autocomplete (<textarea>)
• checkValidity (Constraint validation API)
• cols (<textarea>)
• dirName (dirname)
• labels (<textarea>)
• maxLength (<textarea>)
• minLength (<textarea>)
• reportValidity (Constraint validation API)
• required (<textarea>)
• rows (<textarea>)
• select event (<textarea>)
• selectionchange event (Selection)
• setCustomValidity (Constraint validation API)
• textLength (<textarea>)
• type (<textarea>)
• validationMessage (Constraint validation API)
• validity (Constraint validation API)
• willValidate (Constraint validation API)
• wrap (<textarea>)