TypeError: Property 'true' of object [object Object] is not a function

[gajus]

Documentation:

Can also be used as a function, which prevents some linter errors.
expect(true).to.be.true();

http://chaijs.com/api/bdd/

However, executing:

var expect = require('chai').expect;
expect(true).to.be.true();

Gives:

TypeError: Property 'true' of object [object Object] is not a function

The only variation that I found to work (in function call format) is:

expect(true).to.equal(true);

[keithamus]

Hi @gajus, thanks for the issue. Are you using Chai 1.10? It is the only version of Chai with that feature. Sadly though, it'll have to be removed in the next Chai release because it breaks some existing code. Having said that, there is a plugin available called dirty-chai which overrides the behaviour, I'd recommend using that.

For reference: this is a duplicate of #321 which contains the same information.