Invoke code completion using only the terminal

lsp-standalone.sh

#!/bin/bash

CODE='console.'

INIT='{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"processId":1,"rootUri":null,"capabilities":{}}}'
INITIALIZED='{"jsonrpc":"2.0","method":"initialized","params":{}}'
DIDOPEN="{\"jsonrpc\":\"2.0\",\"method\":\"textDocument/didOpen\",\"params\":{\"textDocument\":{\"uri\":\"file:///dev/null\",\"languageId\":\"typescript\",\"version\":1,\"text\":\"$CODE\"}}}"
COMPLETION="{\"jsonrpc\":\"2.0\",\"id\":2,\"method\":\"textDocument/completion\",\"params\":{\"textDocument\":{\"uri\":\"file:///dev/null\"},\"position\":{\"line\":0,\"character\":${#CODE}}}}"

{
  printf 'Content-Length: %d\r\n\r\n%s' $(echo -n "$INIT"        | wc -c) "$INIT"
  printf 'Content-Length: %d\r\n\r\n%s' $(echo -n "$INITIALIZED" | wc -c) "$INITIALIZED"
  printf 'Content-Length: %d\r\n\r\n%s' $(echo -n "$DIDOPEN"     | wc -c) "$DIDOPEN"; sleep 0.3
  printf 'Content-Length: %d\r\n\r\n%s' $(echo -n "$COMPLETION"  | wc -c) "$COMPLETION"; sleep 0.3
} | typescript-language-server --stdio | tail -n1 | jq -r '.result.items[].label'