Convert Typescript object to json

ts-to-json.py

import re
import sys
import os

filename=sys.argv[1]

newline = ""

with open(filename, 'r') as file:
    for line in file.readlines():
        line= line.replace("'", "\"")
        found = re.search("([a-zA-Z]+):", line)
        if found is not None:
            span = found.span()
            hit = found.string[span[0]: span[1] - 1]
            newline += re.sub(hit[0:], f"\"{hit[0:]}\"", line)
        else:
            newline += line

newline = re.sub(",[\n\r][\s]+}", "}", newline)
newline = re.sub("},[\n\r][\s]+\]", "}]", newline)

with open(filename, 'w') as file:
    file.write(newline)