fix(module:dropdown): unable to set bool attr to false

[kerwin612]

fix(module:dropdown): unable to set bool attr to false

The issue of not being able to update the value of a boolean attribute to false externally needs to be corrected.

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What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
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What is the current behavior?

Issue Number: N/A

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.50%. Comparing base (beeb52d) to head (393206f).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8620      +/-   ##
==========================================
- Coverage   91.51%   91.50%   -0.02%     
==========================================
  Files         534      534              
  Lines       18425    18425              
  Branches     2905     2905              
==========================================
- Hits        16862    16860       -2     
- Misses       1243     1244       +1     
- Partials      320      321       +1     

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[HyperLife1119]

Here, nzVisible and nzDisabled are of type SimpleChange, not boolean. So I guess we don't need to use undefined to determine that, WDYT?

[kerwin612]

nzVisible and nzDisabled receive boolean values externally, but when fetching their values from the changes object, there can be three possible scenarios: undefined (when the external value has not been changed), true (change to true from false), or false (change to false from true). However, if the code logic is simply if(nzVisible), it will only process the case where it is true. When the external source intends to change it to false, it will not take effect as expected.

[HyperLife1119]

I think you misunderstood that when nzDisabled is changed to false, changes.nzDisabled is of type SimpleChange, not boolean, because it's changes.nzDisabled, not this.nzDisabled.