Frequent occurrence when a variable is utilized prior to being assigned

Question

Frequent occurrence when a variable is utilized prior to being assigned

I am currently working with a module

import pino, { Logger } from 'pino';

let logger: Logger;

if (process.env.NODE_ENV === 'production') {
    const dest = pino.extreme();
    logger = pino(dest);
}

if (process.env.NODE_ENV === 'development') {
    // @ts-ignore
    logger = pino({ prettyPrint: { colorize: true } });
}

...

export default logger;
// ^^^ [ts] Variable 'logger' is used before being assigned. [2454]

Under no circumstances is the logger undefined, but even if it were to be undefined, I am okay with that

How do I address the TypeScript error at the end:

Variable 'logger' is used before being assigned. [2454]

I have modified my code, yet the error persists

import pino, { Logger } from 'pino';

let logger: Logger;

if (process.env.NODE_ENV === 'production') {
    const dest = pino.extreme();
    logger = pino(dest);
} else 

if (process.env.NODE_ENV === 'development') {
    // @ts-ignore
    logger = pino({ prettyPrint: { colorize: true } });
} else

if (process.env.NODE_ENV === undefined) {
    throw new Error('Logger must be initialized! Set up process.env.NODE_ENV');
}

if (logger) { // <-- Variable 'logger' is used before being assigned. [2454]
   // configuring process
}

export default logger;

Another approach could be

import pino, { Logger } from 'pino';

let logger: Logger;

function configureProcess(theLogger: Logger) {
  // setup process with theLogger
}

if (process.env.NODE_ENV === 'production') {
    const dest = pino.extreme();
    logger = pino(dest);
    configureProcess(logger); // <-- code duplication
} else if (process.env.NODE_ENV === 'development') {
    // @ts-ignore
    logger = pino({ prettyPrint: { colorize: true } });
    configureProcess(logger); // <-- code duplication
}

if (process.env.NODE_ENV === undefined) {
    throw new Error('Logger must be initialized! Set up process.env.NODE_ENV');
}

export default logger;
// ^^^ [ts] Variable 'logger' is used before being assigned. [2454]

I find myself in a constant battle against TypeScript instead of focusing on development - so many workarounds for an issue that isn't actually a problem

typescript

Answer 1

Answer №1

even if it ends up being undefined, it suits my needs

While having the logger as undefined may not be ideal, considering your statement:

It is important to make this clear in your code for both the compiler and future maintainers:

switch (process.env.NODE_ENV) {
    case 'production':
        const dest = pino.extreme(); // logs to stdout with no args
        logger = pino(dest);
        break;
    case 'development':
        // @ts-ignore
        logger = pino({ prettyPrint: { colorize: true } });
        break;
    default:
        logger = undefined; // This is acceptable
        break;
}

(Instead of using a switch, you can also use if/else if/else).

Additionally, ensure that the data type for logger allows for undefined as well, as mentioned by VinceOPS:

let logger: Logger | undefined;

Note: Utilizing logger with the potential value of undefined requires careful consideration. Instead of allowing this, consider the following suggestions:

If your code only needs to handle the two specified configurations, you can:

Check for one configuration and assume the other:

if (process.env.NODE_ENV === 'development') {
    case 'development':
        // @ts-ignore
        logger = pino({ prettyPrint: { colorize: true } });
} else { // production
        const dest = pino.extreme(); // logs to stdout with no args
        logger = pino(dest);
}

or

Throw an error for any unaccounted configuration:

switch (process.env.NODE_ENV) {
    case 'production':
        const dest = pino.extreme(); // logs to stdout with no args
        logger = pino(dest);
        break;
    case 'development':
        // @ts-ignore
        logger = pino({ prettyPrint: { colorize: true } });
        break;
    default:
        throw new Error("process.env.NODE_ENV must be either 'production' or 'development' to use this module");
}

If you want to support all three possibilities (production, development, or neither), initialize logger to a valid Logger in the third branch as well, such as a "do nothing" logger.

This approach is more effective than allowing logger to be undefined.

Answer 2

even if it ends up being undefined, it suits my needs

While having the logger as undefined may not be ideal, considering your statement:

It is important to make this clear in your code for both the compiler and future maintainers:

switch (process.env.NODE_ENV) {
    case 'production':
        const dest = pino.extreme(); // logs to stdout with no args
        logger = pino(dest);
        break;
    case 'development':
        // @ts-ignore
        logger = pino({ prettyPrint: { colorize: true } });
        break;
    default:
        logger = undefined; // This is acceptable
        break;
}

(Instead of using a switch, you can also use if/else if/else).

Additionally, ensure that the data type for logger allows for undefined as well, as mentioned by VinceOPS:

let logger: Logger | undefined;

Note: Utilizing logger with the potential value of undefined requires careful consideration. Instead of allowing this, consider the following suggestions:

If your code only needs to handle the two specified configurations, you can:

Check for one configuration and assume the other:

if (process.env.NODE_ENV === 'development') {
    case 'development':
        // @ts-ignore
        logger = pino({ prettyPrint: { colorize: true } });
} else { // production
        const dest = pino.extreme(); // logs to stdout with no args
        logger = pino(dest);
}

or

Throw an error for any unaccounted configuration:

switch (process.env.NODE_ENV) {
    case 'production':
        const dest = pino.extreme(); // logs to stdout with no args
        logger = pino(dest);
        break;
    case 'development':
        // @ts-ignore
        logger = pino({ prettyPrint: { colorize: true } });
        break;
    default:
        throw new Error("process.env.NODE_ENV must be either 'production' or 'development' to use this module");
}

If you want to support all three possibilities (production, development, or neither), initialize logger to a valid Logger in the third branch as well, such as a "do nothing" logger.

This approach is more effective than allowing logger to be undefined.

Answer 3

Answer №2

To put it simply, assuming the following criteria:

even if there is a possibility of it being undefined, it works for me

Substitute:

let logger: Logger;

With:

let logger: Logger | undefined;

If logger has the potential to be undefined, indicate that it is potentially undefined. Then tsc will not raise any issues.

Answer 4

To put it simply, assuming the following criteria:

even if there is a possibility of it being undefined, it works for me

Substitute:

let logger: Logger;

With:

let logger: Logger | undefined;

If logger has the potential to be undefined, indicate that it is potentially undefined. Then tsc will not raise any issues.

Answer 5

Answer №3

It is not necessary for the assignment to undefined, as long as your branching logic covers all possibilities, the compiler will recognize that logger will be assigned.

Assuming you only plan to support two logging modes, either production or development, simply use an if/else statement and the compiler will be satisfied.

import pino, { Logger } from 'pino';

let logger: Logger;

if (process.env.NODE_ENV === 'production') {
  const dest = pino.extreme(); // logs to stdout with no args
  logger = pino(dest);
} else {
  logger = pino({ prettyPrint: { colorize: true } });
}

if (process.env.NODE_ENV === undefined) {
  throw new Error('Logger must be initialized! Set up process.env.NODE_ENV');
}

export default logger;

Answer 6

It is not necessary for the assignment to undefined, as long as your branching logic covers all possibilities, the compiler will recognize that logger will be assigned.

Assuming you only plan to support two logging modes, either production or development, simply use an if/else statement and the compiler will be satisfied.

import pino, { Logger } from 'pino';

let logger: Logger;

if (process.env.NODE_ENV === 'production') {
  const dest = pino.extreme(); // logs to stdout with no args
  logger = pino(dest);
} else {
  logger = pino({ prettyPrint: { colorize: true } });
}

if (process.env.NODE_ENV === undefined) {
  throw new Error('Logger must be initialized! Set up process.env.NODE_ENV');
}

export default logger;

Answer 7

Answer №4

Here is the completed and operational code snippet

import pino, { Logger } from 'pino';

let logger: Logger;

switch (process.env.NODE_ENV) {
    case 'development':
        // @ts-ignore
        logger = pino({ prettyPrint: { colorize: true } });
        break;
    case 'production':
        const dest = pino.extreme(); // logs to stdout with no args
        logger = pino(dest);
        break;
    default:
        throw new Error('Logger must be initialized! Set up process.env.NODE_ENV');
}

// Implementation of setting up the process using the logger
setInterval(() => logger && logger.flush(), 10000).unref();

export default logger;

Answer 8

Here is the completed and operational code snippet

import pino, { Logger } from 'pino';

let logger: Logger;

switch (process.env.NODE_ENV) {
    case 'development':
        // @ts-ignore
        logger = pino({ prettyPrint: { colorize: true } });
        break;
    case 'production':
        const dest = pino.extreme(); // logs to stdout with no args
        logger = pino(dest);
        break;
    default:
        throw new Error('Logger must be initialized! Set up process.env.NODE_ENV');
}

// Implementation of setting up the process using the logger
setInterval(() => logger && logger.flush(), 10000).unref();

export default logger;

Frequent occurrence when a variable is utilized prior to being assigned

Answer №1

Answer №2

Answer №3

Answer №4

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