Binary Search for Javascript Arrays

Sean Murphy — Wed, 29 Apr 2009 21:41:12 +0000

If you need to search through a large array, or you search arrays frequently in your Javascript code, or if you do both, chances are a binary search will give you better performance than a linear search (read: for loop). One caveat, however, is that binary search algorithms only work on sorted arrays. Here is a binary search function I sometimes use in my code:

Array.prototype.binSearch = function(needle, case_insensitive) {
    if (!this.length) return -1;

	var high = this.length - 1;
	var low = 0;
	case_insensitive = (typeof(case_insensitive) !== 'undefined' && case_insensitive) ? true:false;
	needle = (case_insensitive) ? needle.toLowerCase():needle;

	while (low <= high) {
		mid = parseInt((low + high) / 2)
		element = (case_insensitive) ? this[mid].toLowerCase():this[mid];
		if (element > needle) {
			high = mid - 1;
		} else if (element < needle) {
			low = mid + 1;
		} else {
			return mid;
		}
	}

	return -1;
};

Recursive Find and Replace With grep and Perl

Sean Murphy — Sat, 11 Apr 2009 20:51:56 +0000

I thought it might be a nice idea to start posting useful little commands and bits of code every now and then–ones I’ve found to be particularly useful. So here’s the first one, recursive find and replace. A masterfully crafted regular expression paired with this command can save you hours of tedious work.

This will search all files recursively for SEARCH_STRING and replace all occurrences of SEARCH_STRING with REPLACE_STRING throughout each unique file found. It also creates a backup of each modified file so that FILE is backed-up as FILE~ (with a tilde).

grep -R --files-with-matches 'SEARCH_STRING' . | sort | uniq | xargs perl -pi~ -e 's/SEARCH_STRING/REPLACE_STRING/'

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Binary Search for Javascript Arrays

Recursive Find and Replace With grep and Perl