Convert string comparison chain to array.includes()

Replace || value === 'aString' and && value !== 'aString' chains with array.includes().

Convert string comparison chain to array.includes()

This refactoring replaces string comparison chains with an array.includes() call. It works for regular string comparisons with || === and for negated string comparisons with && !==. When the string comparison is negated, the .includes call is prefixed with !.


if ( === "value1" 
    || === "value2" 
    || === "value3") {
    // ...


if (["value1", "value2", "value3"].includes( {
    // ...

Why is this refactoring helpful?

Converting a sequence of string comparisons into an array.includes call makes it easy to add or remove elements and enables extracting the string array into a variable.

What do I need to consider?

The compared expression is only evaluated once

For example, consider refactoring

f() === "a" || f() === "b"


["a", "b"].includes(f())

Before the refactoring, f is called one or two times. After the refactoring (with .includes()) f is only called once.

If f has a side effect, this side effect would have been called a different number of times, potentially changing the behavior. This behavior applies not just to function and methods calls but also to getters that can potentially have side effects.


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