Highlighting not working properly when setting value of textarea using jquery

I have textarea as follows and highlighted word using highlightTextarea:

````
$('textarea').highlightTextarea({
words: ['brand']
})
````
When I try to set the value of textarea using jquery:
```
$('textarea').val('changed_value == 9')
```
again called following method :
````
$('textarea').highlightTextarea({
words: ['brand']
})
````
then output is as follows:

It is not reseting the mark tag.
Only after I try to edit the textarea value by typing, it removes the highlighted mark from background.