I'm considering creating a programming language to be used on the internet, are you saying it would be a bad idea to make all numbers in my new language floating point?
Some people feel strongly against this, but for dynamically typed language I enjoy its simplicity (for static languages, type systems are meant to enforce constraints on types, so multiple number types can be useful). It has done well in [at least] javascript and lua, and while the former is anything but an example in how to design a programming language, IMHO, the latter may be.
So no, it wouldn't be a bad idea to make all numbers 64-bit floats. It sounds like you might likely be compiling to javascript, in which case using 64-bit floats will mean you have one less problem to deal with while implementing it.