patwasalinguist•2y ago

Is inspecting import.meta.url a reliable way to distinguish browser and deno contexts?

I have been trying to figure out a good pattern to import JSON that will work whether called in deno or the browser. This is what I was thinking:

let data

if(import.meta.url.startsWith('file')){ // we’re in deno
  let jsonstring = await Deno.readTextFile('delete.json')
  data = JSON.parse(jsonstring)  
} else if(import.meta.url.startsWith('http')){ // we’re in the browser
  let response = await fetch('delete.json')
  data = await response.json()
}

export {data}

let data

if(import.meta.url.startsWith('file')){ // we’re in deno
  let jsonstring = await Deno.readTextFile('delete.json')
  data = JSON.parse(jsonstring)  
} else if(import.meta.url.startsWith('http')){ // we’re in the browser
  let response = await fetch('delete.json')
  data = await response.json()
}

export {data}

I would welcome advice as to whether this is a good approach to this problem. thanks 🙏

4 Replies

crowlKats•2y ago

you could just use fetch for both

patwasalinguistOP•2y ago

hmm. i get this if i $ deno run --allow-read import-data.js

error: Uncaught TypeError: Invalid URL: './delete.json'
  let response = await fetch('./delete.json')

error: Uncaught TypeError: Invalid URL: './delete.json'
  let response = await fetch('./delete.json')

in other words, i'm running it as a shell script and not a deno server, if i'm explaining that correctly hmm, this seems to work

  let url = new URL('./delete.json', import.meta.url).href
  let response = await fetch(url)
  let data = await response.json()

  let url = new URL('./delete.json', import.meta.url).href
  let response = await fetch(url)
  let data = await response.json()

ioB•2y ago

^ I did this at deno-gfm: https://github.com/denoland/deno-gfm/blob/main/example/main.ts basically exactly what you're proposing

patwasalinguistOP•2y ago

nice thanks! gotta ❤️ deno