How to use the roosterjs-editor-dom.matchWhiteSpaces function in roosterjs-editor-dom

}

        let previousInline = this.backwardTraverser.getPreviousInlineElement();
        while (!this.backwardTraversingComplete) {
            if (previousInline && previousInline.isTextualInlineElement()) {
                let textContent = previousInline.getTextContent();
                if (!this.inlineBeforeCursor) {
                    // Make sure the inline before cursor is a non-empty text inline
                    this.inlineBeforeCursor = previousInline;
                }

                // build the word before cursor if it is not built yet
                if (!this.cachedWordBeforeCursor) {
                    // Match on the white space, the portion after space is on the index of 1 of the matched result
                    // (index at 0 is whole match result, index at 1 is the word)
                    let matches = matchWhiteSpaces(textContent);
                    if (matches && matches.length == 2) {
                        this.cachedWordBeforeCursor = matches[1];
                        // if this.cachedTextBeforeCursor is not null, what we get is just a portion of it, need to append this.cachedTextBeforeCursor
                        if (this.cachedTextBeforeCursor) {
                            this.cachedWordBeforeCursor =
                                this.cachedWordBeforeCursor + this.cachedTextBeforeCursor;
                        }
                    }
                }

                this.cachedTextBeforeCursor = !this.cachedTextBeforeCursor
                    ? textContent
                    : textContent + this.cachedTextBeforeCursor;

                if (!this.inlineElementsBeforeCursor) {
                    this.inlineElementsBeforeCursor = [previousInline];