Handlebars does not recognize helper

I found this helper online that checks whether a variable is equal to a certain string. I tried to add this helper to my index.hbs file, but I get the following error: Missing helper: "if_eq"

Can someone tell me how I can fix this? I did what they asked me to do in in the official Handlebars docs, so I don't understand. I use NodeJS/Express, but without require('handlebars') or require('express-handlebars'), because that's how express-generator generated it for me.

index.hbs:

<script>
Handlebars.registerHelper('if_eq', function(a, b, opts) {
    if(a == b)
        return opts.fn(this);
    else
        return opts.inverse(this);
});
</script>


    
        [do something]
    
        [do something else]
    

via Zarif