[[analysis-htmlstrip-charfilter]]
=== HTML strip character filter
++++
<titleabbrev>HTML strip</titleabbrev>
++++

Strips HTML elements from a text and replaces HTML entities with their decoded
value (e.g, replaces `&amp;` with `&`).

The `html_strip` filter uses Lucene's
{lucene-analysis-docs}/charfilter/HTMLStripCharFilter.html[HTMLStripCharFilter].

[[analysis-htmlstrip-charfilter-analyze-ex]]
==== Example

The following <<indices-analyze,analyze API>> request uses the
`html_strip` filter to change the text `<p>I&apos;m so <b>happy</b>!</p>` to
`\nI'm so happy!\n`.

[source,console]
----
GET /_analyze
{
  "tokenizer": "keyword",
  "char_filter": [
    "html_strip"
  ],
  "text": "<p>I&apos;m so <b>happy</b>!</p>"
}
----

The filter produces the following text:

[source,text]
----
[ \nI'm so happy!\n ]
----

////
[source,console-result]
----
{
  "tokens": [
    {
      "token": "\nI'm so happy!\n",
      "start_offset": 0,
      "end_offset": 32,
      "type": "word",
      "position": 0
    }
  ]
}
----
////

[[analysis-htmlstrip-charfilter-analyzer-ex]]
==== Add to an analyzer

The following <<indices-create-index,create index API>> request uses the
`html_strip` filter to configure a new
<<analysis-custom-analyzer,custom analyzer>>.

[source,console]
----
PUT /my-index-000001
{
  "settings": {
    "analysis": {
      "analyzer": {
        "my_analyzer": {
          "tokenizer": "keyword",
          "char_filter": [
            "html_strip"
          ]
        }
      }
    }
  }
}
----

[[analysis-htmlstrip-charfilter-configure-parms]]
==== Configurable parameters

`escaped_tags`::
(Optional, array of strings)
Array of HTML elements without enclosing angle brackets (`< >`). The filter
skips these HTML elements when stripping HTML from the text. For example, a
value of `[ "p" ]` skips the `<p>` HTML element.

[[analysis-htmlstrip-charfilter-customize]]
==== Customize

To customize the `html_strip` filter, duplicate it to create the basis for a new
custom character filter. You can modify the filter using its configurable
parameters.

The following <<indices-create-index,create index API>> request
configures a new <<analysis-custom-analyzer,custom analyzer>> using a custom
`html_strip` filter, `my_custom_html_strip_char_filter`.

The `my_custom_html_strip_char_filter` filter skips the removal of the `<b>`
HTML element.

[source,console]
----
PUT my-index-000001
{
  "settings": {
    "analysis": {
      "analyzer": {
        "my_analyzer": {
          "tokenizer": "keyword",
          "char_filter": [
            "my_custom_html_strip_char_filter"
          ]
        }
      },
      "char_filter": {
        "my_custom_html_strip_char_filter": {
          "type": "html_strip",
          "escaped_tags": [
            "b"
          ]
        }
      }
    }
  }
}
----
