Is it possible to use the core Node.js Assert module to check if a property exists on an object even if the property is falsy?

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normally we could check if an object has a property by running

var assert = require('assert');
assert(obj.prop);

but if obj.prop exists but is falsy, this won't work. I prefer using the Node.js assert module and would rather avoid other solutions, thanks.

Perhaps the best way to do this is:

    var assert = require('assert');
    assert(prop in obj);

Is it possible to use the core Node.js Assert module to check if a property exists on an object even if the property is falsy?

https://nodejs/api/assert.html

normally we could check if an object has a property by running

var assert = require('assert');
assert(obj.prop);

but if obj.prop exists but is falsy, this won't work. I prefer using the Node.js assert module and would rather avoid other solutions, thanks.

Perhaps the best way to do this is:

    var assert = require('assert');
    assert(prop in obj);

• javascript
• node.js
• assert

• 4 Your second snippet is best, works even if prop is set to undefined. – Jared Smith Commented Feb 18, 2016 at 0:50

2 Answers 2

It is possible to assert that an enumerable property exists on an object. The suggested code works excellently:

var assert = require('assert');
assert(prop in obj);

If the property does not exist, an AssertionError is thrown.

When you try pare the attribute, if is undefined thrown an error, you need hasOwnProperty:

const assert = require('assert');
assert.equals(obj.hasOwnProperty('attribute'), true);