tulipemoutarde.be

Software Developer

Smalltalk, Swift, Java, Obj-C

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I'm currently working at Ta Mère SCRL a small development shop in Belgium.

We mainly do mobile apps (iOS, Android) for clients. We also have a strong interest in Pharo Smalltalk and Rust.

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Javascript, The Good Parts

11 Jan 2011 in book javascript 

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.

return
 {
   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.