That book was created before many alternatives came out; now if you are working in a team project you should look at JavaScript the same way you look at assembler, you know it will be the final thing but you shouldn't be creating it directly, but instead "compiling" from TypeScript, ELM, etc. (langs with no implicit conversions, strong typing, etc)
Those alternatives are nice in startup land, in enterprise consulting land, we get to use what the customer IT department sanctions as allowed programming languages and tools installed on computers for external consultants.
