11–20 of 37 posts
Earlier quoted context omitted.
I think there's also an issue of performance -- it's possible, though unlikely, that the sort could take forever to complete.
Unlikely is an understatement -- the probability of an infinite sequence of PRNG outputs that prevents any sort algorithm from terminating is negligible.
BTW I also just noticed Resig's next advanced JS book is almost done (finally!) http://www.manning.com/resig/ and there is a 50% off code that is working for July 4th - july450 which makes it $16 for the early-edition PDF-only version (or $20+$5 shipping for dead-tree version but it's $25 on amazon anyway) If I learn just one new trick for $16 it's probably worth it.
A few days ago I got an update from Manning:
"What's new?
Chapter 2, "Testing and Debugging" has been added.
Chapter 3, "Functions are fundamental" has been revised.
What's next?
Our next update will be coming quickly, with revised versions of Chapter 4 on closures and Chapter 5 on object-orientation with prototypes.
list = list.sort(function() Math.random() - 0.5); Please don't shuffle an array like this. Array.prototype.sort requires the comparison function to be referentially transparent (i.e. to always return the same result when given the same two elements to compare), otherwise the sort order is undefined. For example, imagine how far from "shuffled" the resulting array will be if a bubble sort is used with a randomised com…
Fisher-Yates is a better idea, of course, since it is pretty short and runs in linear time, but if someone insists on a sort-based one-linear this should work: list.map(function (t) { return [Math.random(), t]; }).sort().map(function (t) { return t[1]; })
Wow, I'm seriously overjoyed to discover the "yield" operator, which I did not know existed (it barely shows up anywhere!). No more hackishly using window.setTimeout() to yield in JS pseudo-thread simulations!
Just note the small print that yield is JS 1.7 Firefox 2 was the first to have JS 1.7 but I dunno if any version of IE has yield, maybe IE9 ?
yield
Optional named function arguments
let (in the 'remove an object from an array' example)
"Convert a string into a charcode list" (both methods)
toSource method on an array ("Array iteration pitfall")
etc.
Wow, I'm seriously overjoyed to discover the "yield" operator, which I did not know existed (it barely shows up anywhere!). No more hackishly using window.setTimeout() to yield in JS pseudo-thread simulations!
Just note the small print that yield is JS 1.7 Firefox 2 was the first to have JS 1.7 but I dunno if any version of IE has yield, maybe IE9 ?
Some of those extensions (e.g. Array Extras) trickled into the wider language, but as far as I know most of them (including let and generators) are confined to Gecko-based browsers still.
+new Date() // 1259359833574
function PrefixInteger(num, length) {
return (num / Math.pow(10, length)).toFixed(length).substr(2);
}
I find some of them horribly obscure +new Date() // 1259359833574 Oh come on, magic constants? How do you check if that's the right number? function PrefixInteger(num, length) { return (num / Math.pow(10, length)).toFixed(length).substr(2); } Is there no sprintf in Javascript? Or did I misunderstand what the function does?
Title: Milliseconds since epoch
list = list.sort(function() Math.random() - 0.5); Please don't shuffle an array like this. Array.prototype.sort requires the comparison function to be referentially transparent (i.e. to always return the same result when given the same two elements to compare), otherwise the sort order is undefined. For example, imagine how far from "shuffled" the resulting array will be if a bubble sort is used with a randomised com…
Fisher-Yates is a better idea, of course, since it is pretty short and runs in linear time, but if someone insists on a sort-based one-linear this should work: list.map(function (t) { return [Math.random(), t]; }).sort().map(function (t) { return t[1]; })