How can I add a console log in this function?

Question

Pretty straight forward question, I'm just trying to get a console log in this es6 function.

const testLinesSelector = state => state.tests.testLines || [];

I've tried:

const testLinesSelector = state => { 
  console.log('INSIDE THE SELECTOR ===> ');
  return {state.tests.testLines || [] }
};

`const testLinesSelector = state => console.log('INSIDE THE SELECTOR ===> ') || state.tests.testLines || [];` — Hassan Imam, Mar 21 '20 at 03:31

score 1 · Accepted Answer · answered Mar 21 '20 at 00:39

Remove the braces in your return statement, like so:

const testLinesSelector = state => { 
  console.log('INSIDE THE SELECTOR ===> ');
  return state.tests.testLines || [];
};

As a side-note, I noticed a lot of ES6 code uses function-variables or function-properties instead of just functions - is there a reason you don’t do this instead?

function testLinesSelector( state ) { 
  console.log('INSIDE THE SELECTOR ===> ');
  return state.tests.testLines || [];
};

There are established patterns in the code base and this is the format they're expecting it to be in. — ghostagent151, Mar 21 '20 at 00:43

Dai · Answer 2 · 2020-03-21T02:54:05.867

Another approach you might consider automating your code using Function.name - though this requires using a named function (a la function foobar() { ... }). There are techniques to get the "name" of an anonymous function or arrow-function in JavaScript but they're more involved and may not be compatible with the "established patterns in the code" you're working with.

But here's how you can do it with named functions:

function annotate( func ) {
    return ( ...args ) => {
        console.log( func.name ); // `Function.name` is supported in ES6.
        return func( ...args );
    };
}

const testLinesSelector = annotate( function testLinesSelector( state ) { return state.tests.testLines || [] } );

How can I add a console log in this function?

2 Answers2