I want to filter by id

Question

I want to filter my array of song by title and id but typescript throwing me error that property tolowercase() does not exit on type number
public querySongs() {
    let    song: Song[] = [];
    song =  this.song.filter((item) => {
        return item.title.toLowerCase().indexOf(this.queryText.toLowerCase()) > -1 ||
        item.id.toLowerCase().indexOf(this.queryText.toLowerCase()) > -1
    });
    this.song = song;
}

filtering by title works fine but by id keeps given me this error
"Property 'toLowerCase' does not exist on type 'number'"

swift gaming · Answer

If the id's are stored as numbers then .toLowerCase() won't work because that only works on string's you need to stringify the id's
 public querySongs() {
    let    song: Song[] = [];
       song =  this.song.filter((item) => { return item.title.toLowerCase().indexOf(this.queryText.toLowerCase()) > -1 ||
            item.id.stringify().toLowerCase().indexOf(this.queryText.toLowerCase()) > -1
    });
        this.song = song;
}

Fahim Bagar · Answer

I think the error is clear enough, the item is dynamically cast as number type. Try to cast it to string by appending .toString()
Instead of
return item.title.toLowerCase()...

Change it like this
return item.title.toString().toLowerCase()

or you can use ternary to identify whether it's string type or not
return typeof item.title === 'string' ? item.title.toLowerCase() : item.title

programmer · Answer

So if error says that the toLowerCase not exist on type number this means that type number can't be "toLowerCase" cuz the number is not a string. Change type to string if your id contains any letters.

I want to filter by id

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