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@vpalos /filter.js
Last active Mar 15, 2018

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JS: A simple search function designed for filtering large lists of strings.
/**
* Demo: http://vpalos.com/sandbox/filter.js/
*
* A generic search algorithm designed for filtering (very) large lists of strings; when an input string
* contains all the parts (words or characters; whitespace is ignored) of the query, spread-out over the text
* then the string is considered to be a match. It works with the way internet browsers (e.g. Firefox, Google
* Chrome) filter address-bar suggestions on user input. It is also quite fast; on my i7 laptop, filtering
* 1) a list of ~23000 items takes around 50ms (yes, milliseconds!);
* 2) a list of ~1 million text items took under 1 second.
* It works both in NodeJS as well as in browser environments (so far I only tested FF and GC).
*
* It has two functioning modes:
* 1) word-mode: each (whitespace-separated) word in the input query must be found **whole** in the text:
* e.g. "foo bar" will match "123foo456bar789" but not "f oo ba r";
* 2) charater-mode: the input query is matched per-character (whitespace is completely ignored):
* e.g. "foo bar" will match "f o o b a r" and even "-f.oo-ba.r-".
*
* Options (values below are the defaults):
* {
* "case": false, // true: case-sensitive
* // false: case-insensitive
*
* "mark": true, // true: returns item numbers + matches with highlighted captures
* // false: returns item numbers only
*
* "prefix": "<strong>", // highlight prefix string
* "suffix": "</strong>", // highlight suffix string
*
* "word": true, // true: whole-word mode
* // false: character mode
*
* "limit": 0 // limit results to this amount
* // 0 means return the whole result (unlimited)
* }
*
* @param {string} query The search query, consisting of space-separated chunks of characters.
* @param {string|array} items A string or an array of strings to filter; if a string is given then it is
* first split into an array of individual lines of text and then filtered (note
* that).
* @param {string} prefix String which will come before every highlighted substring (i.e. capture).
* @param {string} suffix String which will come after every highlighted substring (i.e. capture).
* @return {object} Returns the following object with matched items information:
* {
* "items": [...], // array of matched item-numbers
* "marks": [...] // if mark == true, array of matches with highlighted captures
* }
*/
function filter(query, items, options) {
// option producer
function option(name, value) {
options = options || {};
return typeof(options[name]) !== 'undefined' ? options[name] : value;
}
// prepare options
var o_case = option("case", false);
var o_mark = option("mark", true);
var o_prefix = option("prefix", "<strong>");
var o_suffix = option("suffix", "</strong>");
var o_word = option("word", true);
var o_limit = option("limit", 0);
// prepare query
query = o_case ? query : query.toLowerCase();
query = query.replace(/\s+/g, o_word ? ' ' : '');
query = query.replace(/(^\s+|\s+$)/g, '');
query = query.split(o_word ? ' ' : '');
var ql = query.length;
// prepare items
if (typeof(items) === "string") {
items = items.split('\n');
}
// prepare results
var matches = {
items: [],
marks: []
};
// search
for (var ii = 0, il = items.length; ii < il; ii++) {
// prepare text
var text = o_case ? items[ii] : items[ii].toLowerCase();
var mark = "";
// traverse
var ti = 0;
var wi = 0;
var wl = 0;
for (var qi = 0; qi < ql; qi++) {
wl = query[qi].length;
wi = text.indexOf(query[qi], ti);
if (wi === -1) {
break;
}
if (o_mark) {
if (wi > 0) {
mark += items[ii].slice(ti, wi);
}
mark += o_prefix + items[ii].slice(wi, wi + wl) + o_suffix;
}
ti = wi + wl;
}
// capture
if (qi == ql) {
if (o_mark) {
mark += items[ii].slice(ti);
matches.marks.push(mark);
}
if (matches.items.push(ii) === o_limit && o_limit) {
break;
}
}
}
// ready
return matches;
}
@Kjaer

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Kjaer Nov 19, 2017

If you describe the algrorithm, it will be useful for people like me,

UPDATE : I am trying understand the code a couple of hours, Only the logic that I got is using indexOf, rest of the code emphasize the results only ( I mean second for...loop and capture part) it is still super fast, definetely. I might expecting filter function backed by some known algorithm, but I couldn't match any. If you do, please enlight me.

Kjaer commented Nov 19, 2017

If you describe the algrorithm, it will be useful for people like me,

UPDATE : I am trying understand the code a couple of hours, Only the logic that I got is using indexOf, rest of the code emphasize the results only ( I mean second for...loop and capture part) it is still super fast, definetely. I might expecting filter function backed by some known algorithm, but I couldn't match any. If you do, please enlight me.

@ngohuunam

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ngohuunam Jan 15, 2018

How I would like to filter first char instead of whole line?

ngohuunam commented Jan 15, 2018

How I would like to filter first char instead of whole line?

@koganei

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koganei Mar 15, 2018

Hi, what's the license on this code? MIT?

koganei commented Mar 15, 2018

Hi, what's the license on this code? MIT?

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