CKEditor walker get prev character

by sauravmishra

HTML

<script src="http://cdnjs.cloudflare.com/ajax/libs/ckeditor/4.2/ckeditor.js"></script>
<textarea id="editor">
    <blockquote><a href="foo">^Foo</a></blockquote>
    <p>^Hello <strong>world</strong>!</p>
</textarea>    

<button type="button" onclick="console.log( getPrevChar() )">Get previous char</button>

JavaScript

var editor = CKEDITOR.replace( 'editor', {
    plugins: 'wysiwygarea,sourcearea,basicstyles,toolbar',
    allowedContent: true
} );

function getPrevChar() {
    var range = editor.getSelection().getRanges()[ 0 ],
        startNode = range.startContainer;

    if ( startNode.type == CKEDITOR.NODE_TEXT && range.startOffset )
        // Range at the non-zero position of a text node.
        return startNode.getText()[ range.startOffset - 1 ];
    else {
        // Expand the range to the beginning of editable.
        range.collapse( true );
        range.setStartAt( editor.editable(), CKEDITOR.POSITION_AFTER_START );

        // Let's use the walker to find the closes (previous) text node.
        var walker = new CKEDITOR.dom.walker( range ),
            node;

        while ( ( node = walker.previous() ) ) {
            // If found, return the last character of the text node.
            if ( node.type == CKEDITOR.NODE_TEXT )
                return node.getText().slice( -1 );         
        }
    }
    
    // Selection starts at the 0 index of the text node and/or there's no previous text node in contents.
    return null;
}