How to use standard javascript functions in vue?

Question

JavaScript

Such a question arose when it was required to execute indexOf()
And he did not want to be executed with the error
Cannot read property 'indexOf' of undefined
at VueComponent
As in methods

videoShow(url){
      if(url.indexOf('.mp4') != -1){
        return true
      }else{
        return false
      }
    }

So directly in v-if The code gives this error. How to solve the problem?
v-if="url.indexOf('.mp4') !== -1"

Answer 1

Cannot read property 'indexOf' of undefined
It's not about vue, it's about the fact that you didn't pass the url to the method (or it's just undefined)