45 lines
1.2 KiB
Plaintext
45 lines
1.2 KiB
Plaintext
Arrays in JavaScript have several methods for filtering, mapping, or folding that require a callback. Not having a return statement in such a callback function is most likely a mistake, because processing of the array uses the return value of the callback. If there is no return, callback will implicitly return ``++undefined++``, which will likely fail.
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This rule applies for the following methods of an array:
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* ``++Array.from++``
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* ``++Array.prototype.every++``
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* ``++Array.prototype.filter++``
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* ``++Array.prototype.find++``
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* ``++Array.prototype.findIndex++``
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* ``++Array.prototype.map++``
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* ``++Array.prototype.reduce++``
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* ``++Array.prototype.reduceRight++``
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* ``++Array.prototype.some++``
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* ``++Array.prototype.sort++``
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== Noncompliant Code Example
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----
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let arr = ["a", "b", "c"];
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let merged = arr.reduce(function(a, b) {
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a.concat(b);
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}); // Noncompliant: No return statement, will result in TypeError
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----
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== Compliant Solution
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----
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let arr = ["a", "b", "c"];
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let merged = arr.reduce(function(a, b) {
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return a.concat(b);
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}); // merged === "abc"
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----
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ifdef::env-github,rspecator-view[]
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== Comments And Links
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(visible only on this page)
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include::comments-and-links.adoc[]
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endif::env-github,rspecator-view[]
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