I'm starting to use ReactJS with Github Copilot, i was trying to build a calculator, and needed that the input field clean after click one operation, and copilot suggested:

Class component:

const { total, next, operation } = this. State;
const current = next || total || 0; // What is this doing?

DOM Printing:

<div className="calcresult">
  {current}
</div>

Its working perfectly but i don't know what is the || doing in the variable: current.

CodePudding user response：

I found out that is a short circuit operator, if the first value is falsie it goes to the second, if the first and the second are falsie it goes to the third, if the first variable is empty, indefine or null it goes to the next.

Geeks for Geeks JS Short Circuiting

CodePudding user response：

const current = next || total || 0; // What is this doing?

Let's break this out

• First it checks if next variable if it has true value, a true value can be an integer greater than 0, a non-empty string, a non-empty array. if it is, then the current value will be equal to next
• If next don't have a true value, then it checks the true value of total
• If none of the next and total has a true value, the default value will be 0