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Javascript, The Good Parts

This blog post was written a long time ago and may not reflect my current opinion or might be technically out of date. Read with a grain of salt.

Written on January 11, 2011.

I've just finished to read Javascript: The Good Parts of Douglas Crockford. If you’re doing Javascript development you should read it if you haven’t.

This book is not a definitive guide to Javascript but will show you which part of the language to avoid if you want to eliminate a whole class of problems.

Here are some striking (at least for me) examples:

'' == '0'   // false
 0 == ''     // true
 0 == '0'    // true

That’s because == tries to coerce the values if they are of different types.

   status: true

Will not return an object with a status field. It will return undefined. Do you know why?

Another nice one is the parseInt() function.

parseInt('07') // returns 7
 parseInt('08') // returns 0
 parseInt('09') // returns 0

That’s because when the first character of the parsed string is a zero, it is evaluated in base 8. Seriously. In javascript. A high level language. Wow.

Don’t worry, the book is not only a compilation of the weird design choices of Javascript. It will guide you through a world without global variables and will show you how to use functions to create modules. You will learn to master the prototypal object model and understand why the new construct in Javascript is evil.

Highly recommended.