HtmlToText Lua Reference Documentation
chilkat.HtmlToText
Current Version: 11.7.0
Markdown version of this page for AI tools (v 11.7.0) · all AI docs
Chilkat.HtmlToText
Convert HTML markup into readable text suitable for display, logging,
indexing, email alternatives, or text-only output.
Decode HTML entities so text such as named entities and numeric
character references becomes normal readable output.
Use
Suppress hyperlink URLs for cleaner text, or emit URLs when the output
needs to preserve the destination of HTML links.
Convert HTML directly from a
Read HTML from files and write text output using a specified character
encoding.
For an extended overview, see
HtmlToText Class Overview.
Convert HTML into readable plain text with control over links, wrapping, and encoding.
Chilkat.HtmlToText converts HTML content into readable plain
text. It can decode HTML entities, wrap output at a configurable right
margin, optionally include or suppress hyperlink URLs, convert HTML supplied
as a string or StringBuilder, and read or write files using an
explicit character encoding.
HTML to plain text
Entity decoding
Line wrapping
RightMargin to wrap text at a chosen width, or set it to
0 when no right-margin wrapping is wanted.
Link handling
StringBuilder support
StringBuilder when working with
larger or incrementally built HTML content.
File and charset helpers
StringBuilder, choose
whether to decode entities and include link URLs, set the desired right
margin, then convert the result to plain text. Use
HtmlToText when the goal is readable text, not structured XML
or DOM-style parsing.
Object Creation
local chilkat = require("chilkat")
local html_to_text = chilkat.HtmlToText.new()Creates the object (chilkat.HtmlToText() does the same). Lua's garbage collector frees it when it is no longer referenced; html_to_text:dispose() frees it at once, and in Lua 5.4 and later local html_to_text <close> = chilkat.HtmlToText.new() frees it when the block ends. Calling a method of a disposed object raises an error.
Errors
A method that fails returns nil followed by the error text, as io.open does: local body, err = html_to_text:method(...), where err is the object's last_error_text. Wrap the call in assert() to raise an error with that text instead. Methods that answer a question return true or false, numbers are returned as they are (check last_method_success where the description says a value means failure), and property reads and writes never fail for Chilkat reasons.
Misuse raises a Lua error: a wrong argument type or a missing argument (bad argument #1 to ...), an unknown property name, a write to a read-only property, an out-of-range integer, or an object of the wrong class.
Names are Chilkat's in snake_case: QuickGetStr is quick_get_str, LastErrorText is last_error_text. Properties are fields (html_to_text.verbose_logging = true) and methods use the colon (html_to_text:method(...)). Strings are UTF-8; binary data is a Lua string of bytes. Indexes are 0-based, as in every Chilkat API. Unlocking: call chilkat.unlock_bundle("...") once at startup.
Properties
DebugLogFilePath
local strVal = html_to_text.debug_log_file_path
html_to_text.debug_log_file_path = strVal
If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.
Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.
Possible causes of hangs include:
- A timeout property set to 0, indicating an infinite timeout.
- A hang occurring within an event callback in the application code.
- An internal bug in the Chilkat code causing the hang.
DecodeHtmlEntities
local boolVal = html_to_text.decode_html_entities
html_to_text.decode_html_entities = boolVal
Controls whether HTML character references are decoded when converting HTML to plain text. The default value is true.
| Value | Behavior |
|---|---|
true |
HTML entities and numeric character references are decoded to their corresponding characters. For example, & becomes &. |
false |
Character references are left encoded in the plain-text output. |
true when the goal is human-readable text. Set it to false when the original entity notation itself must be preserved.
LastErrorHtml
local strVal = html_to_text.last_error_html
Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastErrorText
local strVal = html_to_text.last_error_text
Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
LastErrorXml
local strVal = html_to_text.last_error_xml
Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastMethodSuccess
local boolVal = html_to_text.last_method_success
html_to_text.last_method_success = boolVal
Indicates the success or failure of the most recent method call: true means success, false means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.
RightMargin
local intVal = html_to_text.right_margin
html_to_text.right_margin = intVal
Controls line wrapping in the generated plain text. The default value is 80. As a line approaches the configured margin, Chilkat attempts to wrap at a SPACE character. Set this property to 0 to disable right-margin wrapping.
SuppressLinks
local boolVal = html_to_text.suppress_links
html_to_text.suppress_links = boolVal
Controls whether hyperlink destination URLs are included in the generated plain text. The default value is true.
| Value | Behavior |
|---|---|
true |
The visible anchor text is retained, but hyperlink destination URLs are omitted. |
false |
Hyperlink URLs are included. By default, they are collected in a References: section at the end of the plain text. |
SuppressLinks set to false, an HTML link whose visible text is chilkat and whose URL is https://www.chilkatsoft.com/ produces the visible text and a numbered reference at the end of the output.
UncommonOptions can be used to suppress the trailing references list with NoReferencesList or emit URLs inline with EmitUrls.
UncommonOptions
local strVal = html_to_text.uncommon_options
html_to_text.uncommon_options = strVal
Specifies uncommon HTML-to-text conversion options as a comma-separated list of keywords. The default is the empty string, which is appropriate for normal use.
| Keyword | Effect |
|---|---|
NoReferencesList |
Does not generate the hyperlink-reference list at the end of the plain-text output. |
EmitUrls |
Emits hyperlink URLs inline in the plain-text output instead of relying on the default trailing reference list. |
SuppressLinks is true, hyperlink URLs are suppressed.
VerboseLogging
local boolVal = html_to_text.verbose_logging
html_to_text.verbose_logging = boolVal
If set to true, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is false. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
Version
local strVal = html_to_text.version
Methods
ToText
-- str is a string, or nil and err on failure
local str, err = html_to_text:to_text(html)
Converts the HTML in html to readable plain text and returns the result.
The conversion honors DecodeHtmlEntities, RightMargin, SuppressLinks, and UncommonOptions. HTML markup is interpreted to produce readable text rather than simply being removed with a tag-stripping operation.
Returns the string, or nil, err on failure (or when nothing is found). The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.
ToTextSb
-- ok is true, or nil and err on failure
local ok, err = html_to_text:to_text_sb(sb)
Converts the HTML currently contained in sb to plain text in place. On success, the same StringBuilder contains the converted plain-text result.
The conversion honors DecodeHtmlEntities, RightMargin, SuppressLinks, and UncommonOptions.
StringBuilder and you want the conversion result returned through that same object rather than as a separate string.
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.