ReactJS toLowerCase is not a function

I am doing a comparison by converting my text to lowercase and comparing its index to -1, in order to have some value to the particular field in ReactJS, but I am getting this error in JavaScript console:

Uncaught TypeError: props.filterText.toLowerCase is not a function

var props = this.props;
var rows = this.props.episodes
        return episode.title.toLowerCase().indexOf(props.filterText.toLowerCase()) > -1;
       return <EpisodeRow key={episode.title} episode={episode}/>


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Method 1

Looks like Chris’s comment is the correct answer:

If title is a string, use toString() before toLowerCase():

return episode.title.toString().toLowerCase().indexOf(props.filterText.toString().toLowerCase()) > -1;

Method 2

I think I found the problem 🙂

props.filterText is undefined.
=> The filterText:”” must be declared in the state before putting in props

Method 3

I think Adam’s answer from the comments is actually correct, and turned out to solve my problem :

    if(episode.title) {
        return episode.title.toLowerCase().indexOf(props.filterText.toLowerCase()) > -1;
    } else {
        return '';

All methods was sourced from or, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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