.addChainableMethod(ctx, name, method, chainingBehavior)

Adds a method to an object, such that the method can also be chained.

utils.addChainableMethod(chai.Assertion.prototype, 'foo', function (str) {
    var obj = utils.flag(this, 'object');
    new chai.Assertion(obj).to.be.equal(str);
});

Can also be accessed directly from chai.Assertion.

chai.Assertion.addChainableMethod('foo', fn, chainingBehavior);

The result can then be used as both a method assertion, executing both method and chainingBehavior, or as a language chain, which only executes chainingBehavior.

expect(fooStr).to.be.foo('bar');
expect(fooStr).to.be.foo.equal('foo');