Make an assertion that actual and expected are almost equal numbers through a given tolerance. It can be used to take into account IEEE-754 double-precision floating-point representation limitations. If the values are not almost equal then throw.

Make an assertion that actual and expected are equal, deeply. If not deeply equal, then throw.

Make an assertion that obj is an instance of type. If not then throw.

Make an assertion that actual match RegExp expected. If not then throw.

Executes a function, expecting it to throw. If it does not, then it throws. An error class and a string that should be included in the error message can also be asserted. Or you can pass a callback which will be passed the error, usually to apply some custom assertions on it.