string.concat() is not useful (#37122)

* Update string/concat/index.md Add {{optional_inline}}, same as array/concat * Update index.md --------- Co-authored-by: Joshua Chen <[email protected]>
mdn · Dec 6, 2024 · c7ee557 · c7ee557
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commit c7ee557
Showing 1 changed file with 1 addition and 2 deletions.
diff --git a/files/en-us/web/javascript/reference/global_objects/string/concat/index.md b/files/en-us/web/javascript/reference/global_objects/string/concat/index.md
@@ -15,7 +15,6 @@ the string arguments to this string and returns a new string.
 ## Syntax
 
 ```js-nolint
-concat()
 concat(str1)
 concat(str1, str2)
 concat(str1, str2, /* …, */ strN)
@@ -24,7 +23,7 @@ concat(str1, str2, /* …, */ strN)
 ### Parameters
 
 - `str1`, …, `strN`
-  - : One or more strings to concatenate to `str`.
+  - : One or more strings to concatenate to `str`. Though technically permitted, calling `String.prototype.concat()` with no arguments is a useless operation, because it does not result in observable copying (like {{jsxref("Array.prototype.concat()")}}), since strings are immutable. It should only happen if you are [spreading](/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax) an array of strings as arguments, and that array happens to be empty.
 
 ### Return value