Log a variable in an arrow function
Written byPhuoc Nguyen
Created
25 Feb, 2021
Category
Trick
Tags
JavaScript
Have you ever had to debug an 1 line arrow function using
`console.log`? It usually requires us to switch to a multiple lines version such as:js
const formatYmd = (date) => {
console.log(date.toISOString());
return date.toISOString().slice(0, 10);
};You can get rid of that conversion by using the
`||` operator. It works because `console.log()` returns `undefined`, so the `||` will enforce the function to evaluate and return the right side which is our actual function.js
const formatYmd = (date) => console.log(date.toISOString()) || date.toISOString().slice(0, 10);
formatYmd(new Date());
// Print something like `2021-02-25T04:52:39.720Z` in the ConsoleThere is another, less known tip which uses the comma operator:
js
const formatYmd = date => (console.log(...), date.toISOString().slice(0, 10));You will find more useful 1 line-of-code functions on the 1 LOC series.
#See also
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Phước Nguyễn