Document.execCommand()

When an HTML document has been switched to designMode, its document object exposes an execCommand method to run commands that manipulate the current editable region, such as form inputs or contentEditable elements.

Most commands affect the document's selection (bold, italics, etc.), while others insert new elements (adding a link), or affect an entire line (indenting). When using contentEditable, execCommand() affects the currently active editable element.

The Clipboard API can be used instead of execCommand in many cases, but execCommand is still sometimes useful. In particular, the Clipboard API doesn't replace the insertText command, which you can use to programmatically replace text at the cursor while preserving the undo buffer (edit history) in plain textarea and input elements.

A boolean value that is false if the command is unsupported or disabled.

aCommandName

A DOMString specifying the name of the command to execute. See Commands for a list of possible commands.

aShowDefaultUI

A boolean value indicating whether the default user interface should be shown. This is not implemented in Mozilla.

aValueArgument

For commands which require an input argument, is a DOMString providing that information. For example, insertImage requires the URL of the image to insert. Specify null if no argument is needed.

backColor

Changes the document background color. In styleWithCss mode, it affects the background color of the containing block instead. This requires a <color> value string to be passed in as a value argument. Note that Internet Explorer uses this to set the text background color.

bold

Toggles bold on/off for the selection or at the insertion point. Internet Explorer uses the <strong> tag instead of <b>.

ClearAuthenticationCache

Clears all authentication credentials from the cache.

contentReadOnly

Makes the content document either read-only or editable. This requires a boolean true/false as the value argument. (Not supported by Internet Explorer.)

copy

Copies the current selection to the clipboard. Conditions of having this behavior enabled vary from one browser to another, and have evolved over time. Check the compatibility table to determine if you can use it in your case.

createLink

Creates an hyperlink from the selection, but only if there is a selection. Requires a URI string as a value argument for the hyperlink's href. The URI must contain at least a single character, which may be whitespace. (Internet Explorer will create a link with a null value.)

cut

Removes the current selection and copies it to the clipboard. When this behavior is enabled varies between browsers, and its conditions have evolved over time. Check the compatibility table for usage details.

decreaseFontSize

Adds a <small> tag around the selection or at the insertion point. (Not supported by Internet Explorer.)

defaultParagraphSeparator

Changes the paragraph separator used when new paragraphs are created in editable text regions. See Differences in markup generation for more details.

delete

Deletes the current selection.

enableAbsolutePositionEditor

Enables or disables the grabber that allows absolutely-positioned elements to be moved around. The grabber is disabled by default since Firefox 64 (bug 1490641).

enableInlineTableEditing

Enables or disables the table row/column insertion and deletion controls. The controls are disabled by default since Firefox 64 (bug 1490641).

enableObjectResizing

Enables or disables the resize handles on images, tables, and absolutely-positioned elements and other resizable objects. The handles are disabled by default since Firefox 64 (bug 1490641).

fontName

Changes the font name for the selection or at the insertion point. This requires a font name string (like "Arial") as a value argument.

fontSize

Changes the font size for the selection or at the insertion point. This requires an integer from 1-7 as a value argument.

foreColor

Changes a font color for the selection or at the insertion point. This requires a hexadecimal color value string as a value argument.

formatBlock

Adds an HTML block-level element around the line containing the current selection, replacing the block element containing the line if one exists (in Firefox, <blockquote> is the exception — it will wrap any containing block element). Requires a tag-name string as a value argument. Virtually all block-level elements can be used. (Internet Explorer and Edge support only heading tags H1–H6, ADDRESS, and PRE, which must be wrapped in angle brackets, such as "<H1>".)

forwardDelete

Deletes the character ahead of the cursor's position, identical to hitting the Delete key on a Windows keyboard.

heading

Adds a heading element around a selection or insertion point line. Requires the tag-name string as a value argument (i.e. "H1", "H6"). (Not supported by Internet Explorer and Safari.)

hiliteColor

Changes the background color for the selection or at the insertion point. Requires a color value string as a value argument. useCSS must be true for this to function. (Not supported by Internet Explorer.)

increaseFontSize

Adds a <big> tag around the selection or at the insertion point. (Not supported by Internet Explorer.)

indent

Indents the line containing the selection or insertion point. In Firefox, if the selection spans multiple lines at different levels of indentation, only the least indented lines in the selection will be indented.

insertBrOnReturn

Controls whether the Enter key inserts a <br> element, or splits the current block element into two. (Not supported by Internet Explorer.)

insertHorizontalRule

Inserts a <hr> element at the insertion point, or replaces the selection with it.

insertHTML

Inserts an HTML string at the insertion point (deletes selection). Requires a valid HTML string as a value argument. (Not supported by Internet Explorer.)

insertImage

Inserts an image at the insertion point (deletes selection). Requires a URL string for the image's src as a value argument. The requirements for this string are the same as createLink.

insertOrderedList

Creates a numbered ordered list for the selection or at the insertion point.

insertUnorderedList

Creates a bulleted unordered list for the selection or at the insertion point.

insertParagraph

Inserts a paragraph around the selection or the current line. (Internet Explorer inserts a paragraph at the insertion point and deletes the selection.)

insertText

Inserts the given plain text at the insertion point (deletes selection).

italic

Toggles italics on/off for the selection or at the insertion point. (Internet Explorer uses the <em> element instead of <i>.)

justifyCenter

Centers the selection or insertion point.

justifyFull

Justifies the selection or insertion point.

justifyLeft

Justifies the selection or insertion point to the left.

justifyRight

Right-justifies the selection or the insertion point.

outdent

Outdents the line containing the selection or insertion point.

paste

Pastes the clipboard contents at the insertion point (replaces current selection). Disabled for web content.

redo

Redoes the previous undo command.

removeFormat

Removes all formatting from the current selection.

selectAll

Selects all of the content of the editable region.

strikeThrough

Toggles strikethrough on/off for the selection or at the insertion point.

subscript

Toggles subscript on/off for the selection or at the insertion point.

superscript

Toggles superscript on/off for the selection or at the insertion point.

underline

Toggles underline on/off for the selection or at the insertion point.

undo

Undoes the last executed command.

unlink

Removes the anchor element from a selected hyperlink.

useCSS

Toggles the use of HTML tags or CSS for the generated markup. Requires a boolean true/false as a value argument.

Note: This argument is logically backwards (i.e. use false to use CSS, true to use HTML) and unsupported by Internet Explorer. This has been deprecated in favor of styleWithCSS.

styleWithCSS

Replaces the useCSS command. true modifies/generates style attributes in markup, false generates presentational elements.

AutoUrlDetect

Changes the browser auto-link behavior (Internet Explorer only)

An example of how to use execCommand with contentEditable elements on CodePen.

This example shows two very basic HTML editors, one using a <textarea> element and one using a <pre> element with the contenteditable attribute set.

Clicking the "Bold" or "Italic" buttons inserts the appropriate tags in the element, using insertText to preserve the edit history, so the user can undo the action.

HTML

<h2>textarea</h2>

<div class="actions" data-for="textarea">
  <button data-el="b">Bold</button>
  <button data-el="i">Italic</button>
</div>

<textarea class="editarea">Some text.</textarea>

<h2>contenteditable</h2>

<div class="actions" data-for="pre">
  <button data-el="b">Bold</button>
  <button data-el="i">Italic</button>
</div>

<pre contenteditable="true" class="editarea">Some text.</pre>

JavaScript

// Prepare action buttons
const buttonContainers = document.querySelectorAll('.actions');

for (const buttonContainer of buttonContainers) {
  const buttons = buttonContainer.querySelectorAll('button');
  const pasteTarget = buttonContainer.getAttribute('data-for');

  for (const button of buttons) {
    const elementName = button.getAttribute('data-el');
    button.addEventListener('click',
      () => insertText(`<${elementName}></${elementName}>`, pasteTarget) )
  }  
}

// Inserts text at cursor, or replaces selected text
function insertText(newText, selector) {
  const textarea = document.querySelector(selector);
  textarea.focus();

  let pasted = true;
  try {
    if (!document.execCommand("insertText", false, newText)) {
      pasted = false;
    }
  } catch (e) {
    console.error('error caught:', e);
    pasted = false;
  }

  if (!pasted) {
      console.error('paste unsuccessful, execCommand not supported');
  }
}

Result

This feature is not part of any current specification. It is no longer on track to become a standard.

• Clipboard API
• HTMLElement.contentEditable
• document.designMode