scope-logger

What it does

Logs a variable and a sequence of scopes through which it's accessed. It automatically logs the name of the variable. A NodeJs logger. Inspired by the debug library.

Why??

Too lazy to write console.log("variableName %o", variableValue) :)) The same effect can be achieved with console.log({variable}) => $ variableName: variableValue
But this logger shows the sequence of scopes(i.e., functions) from the variable is logged, a feature that I wished I had when I was logging many different variables.

Example

function outerFn() {
  function innerFn() {
    const logger = new Logger("lazy-log");

    const foofoo = "barbar";
    logger.log({ foofoo });
  }

  innerFn();
}

outerFn();

Output:

Installation

$ npm install scope-logger

Usage

1. Create an instance of Logger. Namespace and options are optional args for constructor.

2. Pass the variable you want to log to the log method inside curly brackets {}!

Additional Control

• disableAll() Toggle to disable all the logging of a logger/namespace. A much more efficient approach than commenting every console.log() line (and deleting them) before pushing the code to production. Can be used to get rid of a logger instance's logs in the terminal.

For instance:

const logger = new Logger("Log tester").disableAll();
//or
logger.disableAll();

const foo = "bar";
logger.log({ foo });

Output: nothing! $

Configuration Options

1. ignoreIterators (boolean): set true to omit the native iterator calls (e.g., Array.forEach) in the scope log statement. This applies to all types of array-like iterators available in JS and NodeJs such as Map, Set, Array, Int8Array, and so on.

function outerFn() {
  function innerFn() {
    const logger = new Logger("Server");

    const testArr = [1, 2, 3];
    testArr.forEach((val) => {
      logger.log({ val });
    });
  }

  innerFn();
}

outerFn();

Default output:

testArr.forEach((val) => {
  logger.log({ val }, { ignoreIterators: true });
});

Configured output: Array.forEach is omitted

2. onlyFirstElem (boolean): set to true to log only the first element in an iterator call. This is useful in scenarios where you only care about the scope journey of a variable in the iterator call, but not about the value of each variable.

All the elements would have the same scope signature, therefore it's redundant to print all those logs. The non-first variables are not logged. This applies recursively for nested iterator calls.

function main() {
  const outerArr = [1, 2, 3];
  const innerArr = [1, 2, 3];

  outerArr.forEach(() => {
    innerArr.map((val) => {
      logger.log({ val });
    });
  });
}

main();

Default output: The following 3 lines x 3 = 9 logs in total

outerArr.forEach(() => {
  innerArr.map((val) => {
    logger.log({ val }, { onlyFirstElem: true });
  });
});

Configured output: Only the first element is logged

The default configuration:

  {
    ignoreIterators: false,
    onlyFirstElem: false
  }

Limitations

1. Cannot pass a property of an object. Because the library is based on JS object destructing (console.log({foo}) outputs the same as console.log({foo: <value>})).

• Where foo.name = "bar" Cannot type logger.log({foo.name}). This will throw a syntax error.

Test

$ npm run test