Tight JSON and JavaScript stringify

dev-stringify.ts

function jsReplacer() {
  const seen = new WeakSet();
  return (key: string, value: any) => {
    if (typeof value === "object" && value !== null) {
      if (seen.has(value)) return "[Circular]";
      seen.add(value);
    }
    if (value instanceof RegExp) return { regexp: value.toString() };
    if (value instanceof Function) return { function: value.toString() };
    if (value instanceof Error) return { error: value.toString() };
    if (value instanceof Set) return [...value];
    if (value instanceof Map) return Object.fromEntries(value);
    if (typeof window !== "undefined" && value instanceof window.Node)
      return { node: `<${value.nodeName}/>` };

    return value;
  };
}

export function tightJsonStringify(
  obj: any,
  replacer?: ((this: any, key: string, value: any) => any) | undefined,
) {
  if (obj === undefined) return undefined;
  return JSON.stringify(obj, replacer, 2)
    .replace(/^([{[])\n (\s+)/, "$1$2")
    .replace(/(\n[ ]+[{[])\n\s+/g, "$1 ")
    .replace(/\n\s*([\]}])/g, " $1");
}

export function tightJavaScriptify(value: any): string {
  return javaScriptifyJSON(tightJsonStringify(value, jsReplacer()));
}

export function lineJavaScriptify(value: any): string {
  if (value == null) return String(value);
  return javaScriptifyJSON(JSON.stringify(value, jsReplacer()));
}
function javaScriptifyJSON(json: string | undefined | null): string {
  if (json == null) return String(json);
  return json
    .replace(/([^\\"])"((:?[^"\\]+|\\[^"]|\\")+)"/g, (full, init, inner) => {
      if (inner.includes("\\n")) {
        return `${init}\`${inner
          .replace(/`/g, "\\`")
          .replace(/\\"/g, '"')
          .replace(/([^\\])\\n/g, "$1\n")}\``;
      }
      return full;
    })
    .replace(/(\\?")((?:[^\\"\s-]|\\\1)+)\1:/g, "$2:");
}