Rule change proposal regarding `prefer-ternary`:

[jroru]

Description

prefer-ternary currently only supports

'simple' if-else statements, where 'simple' means the consequent and alternate are each one line and have the same basic type and form.

Would it be possible to also detect the following example?:

Fail

const data = getData();
const defaultData = getDefaultData();

let items = defaultData;

if (data.length) {
    items = data;
}

Pass

const data = getData();
const defaultData = getDefaultData();

const items = data.length ? data : defaultData;

[fisker]

Would it be possible to also detect the following example?

Yes.

[fisker]

Note that they are not really the same, we need check that initial assigned value don't have sideeffect.

[sindresorhus]

This is accepted.

[zaicevas]

I started looking at this. A couple of questions:

we need check that initial assigned value don't have sideeffect.

In other words - whether the initially assigned value is not a function call? FAIL

let items = defaultData;

if (data.length) {
    items = data;
}

PASS

let items = getDefaultData();

if (data.length) {
    items = data;
}

How far do we want to go with this enhancement? For instance, what about those cases:

• multiple statements in if block

let items = defaultData;
let nopers = {};

if (data.length) {
    items = data;
    nopers = 'hey';
    foo();
}

• Reassignments after the declaration

let items = defaultData;

items = fallbackData;

if (data.length) {
    items = data;
}

• Side effects between the assignment and if block

let items = defaultData;

sideEffect()

if (data.length) {
    items = data;
}