Fix: prefer-const when using destructuring assign (fixes #8308) #10924
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@mysticatea if you have time, can you take a look at this pull request? |
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Good call. Let me check that.
…On Wed, Oct 17, 2018 at 10:49 AM Teddy Katz ***@***.***> wrote:
***@***.**** commented on this pull request.
Thanks! I noticed one potential bug, but this generally looks like a good
approach.
------------------------------
In lib/rules/prefer-const.js
<#10924 (comment)>:
> @@ -96,6 +97,47 @@ function getDestructuringHost(reference) {
return node;
}
+/**
+ * Determines if a destructuring assignment node contains
+ * any MemberExpression nodes. This is used to determine if a
+ * variable that is only written once using destructuring can be
+ * safely converted into a const declaration.
+ * @param {ASTNode} node The ObjectPattern or ArrayPattern node to check.
+ * @returns {boolean} True if the destructuring pattern contains
+ * a MemberExpression, false if not.
+ */
+function hasMemberExpressionAssignment(node) {
+ switch (node.type) {
+ case "ObjectPattern":
+ return node.properties.some(prop => {
+ if (prop) {
Will this work correctly if node contains an object rest pattern?
var { ...foo } = bar;
It seems like prop.value would be undefined in that case, which would
cause the recursive call to crash.
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Nicholas C. Zakas
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Author, Principles of Object-Oriented JavaScript <http://amzn.to/29Pmfrm>
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mysticatea
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Oct 18, 2018
kaicataldo
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Oct 19, 2018
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What is the purpose of this pull request? (put an "X" next to item)
[ ] Documentation update
[x] Bug fix (template)
[ ] New rule (template)
[ ] Changes an existing rule (template)
[ ] Add autofixing to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:
What changes did you make? (Give an overview)
Changed
prefer-constso that it considers destructuring assignment with an object property to disqualify usingconstfor variables used in the same destructuring assignment.Is there anything you'd like reviewers to focus on?
Is this the correct approach? It seems like the key to fixing this bug was to consider object properties in destructuring assignment to be the key factor in determining if a variable should be declared with
const. I'm not 100% this is the correct assumption, so please double-check that.