rtfeldman/seamless-immutable

isMergableObject returns true for an empty object

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#82 opened on Dec 28, 2015

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 (1 comment) (0 reactions) (0 assignees)JavaScript (5,367 stars) (221 forks)batch import
bughelp wanted

Description

      function addToResult(currentObj, otherObj, key) {
      var immutableValue = Immutable(otherObj[key]);
      var mergerResult = merger && merger(currentObj[key], immutableValue, config);
      var currentValue = currentObj[key];

      console.log("IS NEW OBJECT MERGABLE", isMergableObject(new Object()));

  -> seamless-immutable.js:306 IS NEW OBJECT MERGABLE true

In my production build currentValue is sometimes an empty object, and with deep merge enabled we error out when trying to call merge() on said object. In dev mode this never seems to happen.

I've worked around this with an additional check to isMergableObject which checks that Object.keys(target).length > 0. If this seems like an acceptable fix I'd love to submit a PR.

Contributor guide

Tech stack
javascript
Domain
developer experience
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaScript basicsimmutable data concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80
Research direction
Examine the `isMergableObject` function in `seamless immutable.js` around line 306. The proposed fix is to add a check that `Object.keys(target).length > 0` to return false for empty objects. Ensure to update any existing tests or add a new test for this edge case. Also investigate why the issue only occurs in production builds; it might be related to JavaScript engine optimizations.