Study notes - Passing a junk of code throught ESLint

The following is a piece of junk code I usually write. Then I end up using ESLint with the Airbnb style set of rules on it. And punished myself to fix all the inconsistencies.

Eslint result

My initial code


class _Promise {
  constructor(user_exec_function) {
    user_exec_function( (data) => { this.resolveMethod(data) } );
    this.endUserThenFunction = null;
  }

  resolveMethod(data) {
    console.log(this.endUserThenFunction);
    this.endUserThenFunction(data);
  }

  then(endPassedThenFunction) {
    this.endUserThenFunction = endPassedThenFunction;
  }
}

function myTest() {
  return new _Promise(
     callBackForCallingThen => {
        setTimeout( ()=> {
            callBackForCallingThen("data")
        },3000);
     }
  );
}

myTest().then(data => {
  console.log('Result is ' + data);
});

The initial eslint test output:


   1:16  error    Block must not be padded by blank lines                                              padded-blocks
   3:14  error    Unexpected space before function parentheses                                         space-before-function-paren
   3:16  error    Identifier 'user_exec_function' is not in camel case                                 camelcase
   4:23  error    There should be no spaces inside this paren                                          space-in-parens
   4:61  error    Missing semicolon                                                                    semi
   4:64  error    There should be no spaces inside this paren                                          space-in-parens
   9:5   warning  Unexpected console statement                                                         no-console
  20:1   error    Expected indentation of 4 spaces but found 5                                         indent
  20:6   error    Expected parentheses around arrow function argument having a body with curly braces  arrow-parens
  21:1   error    Expected indentation of 6 spaces but found 8                                         indent
  21:19  error    There should be no spaces inside this paren                                          space-in-parens
  21:22  error    Missing space before =>                                                              arrow-spacing
  22:1   error    Expected indentation of 8 spaces but found 12                                        indent
  22:36  error    Strings must use singlequote                                                         quotes
  22:43  error    Missing semicolon                                                                    semi
  23:1   error    Expected indentation of 6 spaces but found 8                                         indent
  23:10  error    A space is required after ','                                                        comma-spacing
  24:1   error    Expected indentation of 4 spaces but found 5                                         indent
  24:7   error    Missing trailing comma                                                               comma-dangle
  28:15  error    Expected parentheses around arrow function argument having a body with curly braces  arrow-parens
  29:3   warning  Unexpected console statement                                                         no-console
  29:15  error    Unexpected string concatenation                                                      prefer-template

✖ 22 problems (20 errors, 2 warnings)
  19 errors and 0 warnings potentially fixable with the `--fix` option.

Block must not be padded by blank lines

Removing blank line after the beginning of the block

Unexpected space before function parentheses

Removing space before the function parenthesis

Identifier 'user_exec_function' is not in camel case

Using camel case

There should be no spaces inside this paren

Removing spaces within the parenthesis of function call

Missing semicolon

Adding semicolon within the code block for the arrow function passed as argument to the user function

Expected indentation of 4 spaces but found 5

Fixing Identation

Expected parentheses around arrow function argument having a body with curly braces

Inserting parenthesis to the argument

space-in-parens again

No spaces

There should be space before =>

arrow-spacing now ok

Strings must use single quote

Fixing quotes

Adding semi colon

Missing semicolon

Space after comma

A space is required after ',' ´

Fixing function to become condensed

Removing the necessity to the trailing comma but this is interesting one because, really, if a function could have more arguments, better is to keep a trailing cooma so that its better visualization in the git, always a new line

Parenthesis to the argument of the arrow function

Fixing parentheis

template

Unexpected string concatenation

Code after

class _Promise {
  constructor(userExecutor) {
    userExecutor((data) => { this.resolveMethod(data); });
    this.endUserThenFunction = null;
  }

  resolveMethod(data) {
    console.log(this.endUserThenFunction);
    this.endUserThenFunction(data);
  }

  then(endPassedThenFunction) {
    this.endUserThenFunction = endPassedThenFunction;
  }
}

function myTest() {
  return new _Promise((callBackForCallingThen) => {
    setTimeout(() => {
      callBackForCallingThen('data');
    }, 3000);
  });
}

myTest().then((data = 'default') => {
  console.log(`Result is ${data}`);
});

myPromise instead of _Promise

Also fixed _Promise since the Airbnb rule didn´t catch it.

class myPromise {
  constructor(userExecutor) {
    userExecutor((data) => { this.resolveMethod(data); });
    this.endUserThenFunction = null;
  }

  resolveMethod(data) {
    console.log(this.endUserThenFunction);
    this.endUserThenFunction(data);
  }

  then(endPassedThenFunction) {
    this.endUserThenFunction = endPassedThenFunction;
  }
}

function myTest() {
  return new myPromise((callBackForCallingThen) => {
    setTimeout(() => {
      callBackForCallingThen('data');
    }, 3000);
  });
}

myTest().then((data = 'default') => {
  console.log(`Result is ${data}`);
});

taboca/doc-js-eslint-with-marcio-s-code