Return value of property with specified key in JSON object read from stdin

jsonprop

#!/usr/bin/env node
const args = process.argv.slice(2)
const key = args[0]

if (!key) {
  console.error('Missing argument')
  process.exit(1)
}

let buffer = ''
process.stdin.on('data', (data) => {
  if (data) buffer += data.toString()
})
process.stdin.on('end', () => {
  const obj = JSON.parse(buffer)
  const result = obj[key]
  if (typeof result === 'undefined') {
    process.exit(2)
  }
  console.log(result)
})

• Expects proper JSON (will fail loudly on invalid syntax)
• Takes a single argument: key of property's value to return
• Exits with 0 if named property is undefined
• Only supports plain objects
• Only looks on first level for property key

Example

$ echo '{"foo": "bar","hello":"world","fresh":"water","is":"good"}' | jsonprop fresh
water