'includes()' is for string, not for array in Javascript?

Question

Object.keys()
Returns an array containing the names of all of the given object's own enumerable string properties.

Then why is the following statement valid in the code shown in this SO thread?
https://stackoverflow.com/a/66758849/462608

const colorValues = Object.keys(this.colorValues);
const invalidColors = colors.filter(c => !colorValues.includes(c));

includes works on arrays too: developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… — Nick
– Nick, Commented Mar 24, 2021 at 4:31
You really shouldn't rely on w3schools for information. The MDN developer guides are a much better resource. — Nick
– Nick, Commented Mar 24, 2021 at 4:32
You were checking the string documentation on w3schools, the array one also has its own includes: w3schools.com/jsref/jsref_includes_array.asp — zerkms
– zerkms, Commented Mar 24, 2021 at 4:46

CertainPerformance · Accepted Answer · 2021-03-24 04:32:05Z

3

It exists on both prototypes: String.prototype.includes and Array.prototype.includes.

String.prototype.includes checks if the string contains the passed substring.

Array.prototype.includes checks if the array contains a particular value (with the SameValueZero algorithm).

Somewhat confusingly, they use the exact same name, but the logic employed is similar.

answered Mar 24, 2021 at 4:32

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