<?php


$langs = [
    [1,"Frontend",  0],
    [2,"Backend",   0],
    [3,"Angular",   1],
    [4,"Angular 1", 3],
    [5,"Vue",       1],
    [6,"React",     1],
    [7,"PHP",       2],
    [8,"Laravel",   7],
    [9,"Angular 1.8",  4]
];


//Recursive generating childs function
function generateAllChilds($id, $ar, $n){
	$childs = [];
	for($i = 0; $i < $n; $i++){
		if($id == $ar[$i][2]){
			array_push($childs, (object)[
				"id" => $ar[$i][0],
				"name" => $ar[$i][1],
				"childs" => generateAllChilds($ar[$i][0], $ar , $n)
			]);
		}
	}
	return $childs;
}

function langsToArray($langArray){
    $ret = [];
    $len = count($langArray);

    //Getting root parents
    for($i = 0; $i < $len; $i++){
        if($langArray[$i][2] == 0){
            array_push($ret, (object)[
                "id" => $langArray[$i][0],
                "name" => $langArray[$i][1],
                "childs" => generateAllChilds($langArray[$i][0],$langArray, $len)
            ]);
        }
    }
    return $ret;
}

echo "<pre>";
print_r(langsToArray($langs));
echo "<pre>";

echo $json = json_encode(langsToArray($langs));
echo "<script>console.log('".$json."');</script>";