tinymce-docs-4x/_includes/configuration/br-in-pre.md

br_in_pre

This option allows you to disable TinyMCE's default behavior when pressing the enter key within a pre tag. By default, pressing enter within a pre tag produces a br tag at the insertion point. For example:

<pre>This is inside <br> a pre tag.</pre>

However, when br_in_pre is set to false, rather than inserting a br tag TinyMCE will split the pre tag. For example:

<pre>This is inside </pre> <pre>a pre tag.</pre>

Note: when set to false, shift+enter will insert a br tag.

Type: Boolean

Default Value: true

Possible Values: true, false

Example:

tinymce.init({
  selector: "textarea",  // change this value according to your html
  br_in_pre: false
});