Removing falsies from JavaScript object
So I write a short function to remove members from an object that have falsy values:
for (var key in object) {
if (!object[key]) {
delete object[key];
}
}
A couple days later I check source control and someone has changed this to:
var newObject = {};
for (var key in object) {
if (object[key]) { newObject[key] = object[key]; }
}
return newObject;
There's no comments on the check-in and the开发者_JAVA百科 guy is not here today at work.
Which implementation is better? What are the performance implications of each method?
You cannot delete a property on an object that it inherits from a prototype. So in some cases your code may fail to work as expected.
Source
You cannot delete
a property of an object that it inherits from a prototype
(although you can delete it directly on the prototype).
In the second example, a falsy property inherited from a prototype
will not be copied to the newObject
.
Further reading:
- Mozilla Dev Center: delete Operator
Using Lo-Dash, consider this implementation (using _.pick):
var newObject = _.pick(object, function onlyTruthy(val, key) {
return !!val;
});
I think your code reads much more intuitively. Maybe he just didn't want to change the original object?
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