The includes()
method of String
values performs a case-sensitive search to determine whether a given string may be found within this string, returning true
or false
as appropriate.
The includes()
method of String
values performs a case-sensitive search to determine whether a given string may be found within this string, returning true
or false
as appropriate.
includes(searchString) includes(searchString, position)
searchString
A string to be searched for within str
. Cannot be a regex. All values that are not regexes are coerced to strings, so omitting it or passing undefined
causes includes()
to search for the string "undefined"
, which is rarely what you want.
position
Optional
The position within the string at which to begin searching for searchString
. (Defaults to 0
.)
true
if the search string is found anywhere within the given string, including when searchString
is an empty string; otherwise, false
.
TypeError
Thrown if searchString
is a regex.
This method lets you determine whether or not a string includes another string.
The includes()
method is case sensitive. For example, the following expression returns false
:
"Blue Whale".includes("blue"); // returns false
You can work around this constraint by transforming both the original string and the search string to all lowercase:
"Blue Whale".toLowerCase().includes("blue"); // returns true
const str = "To be, or not to be, that is the question."; console.log(str.includes("To be")); // true console.log(str.includes("question")); // true console.log(str.includes("nonexistent")); // false console.log(str.includes("To be", 1)); // false console.log(str.includes("TO BE")); // false console.log(str.includes("")); // true
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https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/includes