Console-pretty JSON.stringify() alternative for color coded values (atomics and complex objects).

pretty-json-stringify.ts

function prettyJSONStringify(value: string) {
  const color = (str: string, colorCode: number): string => {
    const escape = `\x1b[${
      Array.isArray(colorCode)
      ? `38;2;$${colorCode.join(";")}`
      : colorCode
    }m`;
    return `${escape}${str.replace(/(\x1b\[39m)/g, `$1${escape}`)}\x1b[39m`
  };
  const format = (value: string): string => {
    if (['"undefined"', "null"].includes(value)) {
      return color(value.replace(/"/g, ""), 33);
    }
    if (["true", "false"].includes(value)) {
      return color(value, 34);
    }
    if (/^("|').*\1$/.test(value)) {
      return color(value, 35);
    }
    if (/^\d*(\.\d+)?$/.test(value)) {
      return color(value, 36);
    }
    return `\x1b[2m${value}\x1b[22m`;
  };
  
  return JSON.stringify(value, (_, value: unknown) => (value === undefined) ? `${value}` : value, 2)
  .split(/\n/g)
  .map((line: string) => {
      const parts = line.split(/:(.*)/s);
      if(!parts[1]) return format(line);
      
      const isTrailing = /,$/.test(parts[1]);
      parts[0] = parts[0].slice(0, -1).replace("\"", "");
      parts[1] = parts[1].slice(0, parts[1].length - +isTrailing).trim();
      
      return `\x1b[2m${color(
        !/^[_\w][_\w\d]*$/.test(parts[0].trimStart())
        ? `${parts[0].match(/^\s*/)[0]}'${parts[0].trimStart()}'`
        : parts[0]
      , 33)}:\x1b[22m ${
        format(parts[1])
      }${isTrailing ? "," : ""}`;
  })
  .join("\n");
}