CKEditor Prevent block elements ? like (`div,p,h1,h2, etc`) - ckeditor

Question

How can prevent block elements in ckeditor?
I want to don't let to ckeditor to accept block elements.
With prevent enter key i can do this but if i paste some text that's include enter key or several paragraph in ckeditor everything down.
In other word i want a textbox with ckeditor.

Answer 1

Quoting an official weekly blog post:
CKEditor core developer, Olek Nowodziński, was hacking the editor a bit in his spare time and here is the result...
Editable header that does not break with Enter key or pasted multi–line content: https://jsfiddle.net/540ckczt/
var editor = CKEDITOR.inline( 'editor', {
plugins: 'clipboard,floatingspace,toolbar,undo,basicstyles,link',
toolbar: [ [ 'Undo', 'Redo' ], [ 'Bold', 'Italic' ], [ 'Link', 'Unlink' ] ],
// Enter mode ill be set to BR automatically if editor was enabled on some element
// which cannot contain blocks (like <h1 for instance).
// If you want to enable editor on different elements, set BR mode here.
// Read the note below to learn why.
enterMode: CKEDITOR.ENTER_BR,
on: {
instanceReady: function() {
// Remove all "br"s from the data being inputted into the editor.
editor.dataProcessor.dataFilter.addRules( {
elements: {
br: function() {
return false;
}
}
} );
this.editable().on( 'keydown', function( evt ) {
var keystroke = evt.data.getKeystroke();
if ( keystroke == CKEDITOR.SHIFT + 13 || keystroke == 13 ) {
evt.data.preventDefault();
}
} );
}
}
} );
Note that the crucial part of this code is that the ACF filters out the rest of block tags (other than <br>). In the case above the ACF works in an automatic mode where it's configured by the enabled features. And since there's no Format dropdown or any other feature creating blocks, none of them is allowed. Read more in the Advanced Content Filter guide.
I expect that one could ask now: "Why can't we configure ACF to filter out <br>s too?"
The answer is that ACF must be able to normalise blocks which are not allowed to some content, and as CKEditor does not support "no enter" mode officially, it choses between normalising to <p>, <div> or <br>. The decision is made based on the enter mode, so that's why it's important to configure such editor to enter mode BR.