In Javascript. how can I tell if a field exists inside an object?

user_390370 0
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And of course I want to do this code-wise. It's not that there isn't alternative to this problem I'm facing, just curious.

javascript
5 Answers

There is has method in lodash library for this. It can even check for nested fields. 

_.has(object, 'a');     
_.has(object, 'a.b');
user_76004920

This question is quite old but it still can be useful to some people.

Now, there is an other way to do it which is recommended if you have non-hardcoded keys.

You have to go from this:

foo.hasOwnProperty("bar");

To this:

Object.prototype.hasOwnProperty.call(foo, "bar");

This update is particularly useful, especially if you use a linter like ESLint which has by default this rule in the "eslint:recommended" set of rules. This new way to do it is notably for security reasons. The whole explanation is available on this page.

user_95339770
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