WebStorm error: expression statement is not assignment or call

Question

I\'m using WebStorm and I\'m getting an error that I can\'t understand. Node.js + MongoDB.

var mongoose = require(\'mongoose\');

mongoose.Promise = global.P         


        

Answer 1

You need to change JavaScript Language Version to ES6. Changing this setting should fix the issue:

In some scenarios, you might need to restart your IDE for the changes to reflect properly.

Answer 2

The problem is that WebStorm will show a warning if that statement isn't doing any of the following within a function:

• Calling another function
• Making any sort of assignment
• Returning a value
• (There may be more, but those are the ones I know of)

In other words, WebStorm views that function as unnecessary and tries to help you catch unused code.

For example this will show the warning:

const arr = [1, 2];
const willShowWarning = arr.map(num => {
    num + 1;
});

Adding a return will take the warning away:

const arr = [1, 2];
const willNotShowWarning = arr.map(num => {
    return num + 1;
});

The answer is not to change WebStorm settings.