How to correctly use function in templates

[yimogit]

I now write the function to the template data call ,because I didn't find the relevant documents.
I write this right now， I don't know if it's correct, I hope to get help, thank you.

const ejs = require('ejs')
ejs.delimiter = '%'
var result = ejs.render('<%= capitalize(title) %>', {
  title: 'test',
  capitalize(str) {
    return str ? str.substring(0, 1).toUpperCase() + str.substring(1) : str
  }
})
console.log(result) //Test