related codes
const contains = (() =>
Array.prototype.includes
? (arr, value) => arr.includes(value)
: (arr, value) => arr.some(el => el === value)
)();
contains(["foo", "bar"], "baz"); // => false
const contains = (() =>
Array.prototype.includes
? (arr, value) => arr.includes(value)
: (arr, value) => arr.some(el => el === value)
)();
contains(["foo", "bar"], "baz"); // => falsethis code is too refined. Let's extract the key points:
The contains function defined by returns one function and defines two parameters;
if the original method of the array has a method of includes, it directly returns (arr, value) = > arr.includes (value) where two parameters arr, value;
are defined.
if there is no includes method, (arr, value) = > arr.some (el = > el = value) is returned, where two parameters arr, value;
are also defined.
and there are anonymous expressions outside contains that (), is executed immediately;
when calling contains (['foo',' bar'], 'baz'), it is equivalent to passing [' foo', 'bar'] to arr,' baz' to value.
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