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dounan/sentinel-shallow-copy.js

Last active September 19, 2017 01:08
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Sentinel shallow copy gotcha
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sentinel-shallow-copy.js
const obj = {nested: {}};
const wrappedObj = makeSentinel(obj);
// copiedObj is not a sentinel
const copiedObj = {...wrappedObj};
copiedObj.value = "oops"; // mutation is NOT detected
// copiedObj.nested is a sentinel because it was copied from wrappedObj
copiedObj.nested.value = "oops"; // MUTATION DETECTED!
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