Javascript - how do i do a array group and count it, like in MySQL group by given column id? -

Javascript - how do i do a array group and count it, like in MySQL group by given column id? -

i have big array bellow, need grouping first column , count total of channel existence.

for example:

var original_db = [ ["channel1", "online"], ["channel2", "offline"], ["channel3", "online"], ["channel1", "online"], ["lot more"].... ]

expected result original result need be:

var custom_db = [ ["channel1", 2], ["channel2", 0], ["channel3", 1] ]

edit:

for(var key in original_db) { var i; (i = 0; < original_db.length; += 1) { if (original_db[i][0] === original_db[key][0]) { original_db.splice(i, 1); return; } } } console.log(original_db);

use object properties first elements maintain count:

var counts = {}; (var = 0; < original.length; i++) { var key = original[i][0]; if (counts[key]) { counts[key]++; } else { counts[key] = 1; } }

you can turn final array, although i'm not sure why prefer on counts object:

final = []; (var key in counts){ final.push([key, counts[key]]); }

javascript multidimensional-array duplicates