JSON stringify function that compacts numeric arrays, putting brackets and values on the same line

compactify.js

function compactify(ugly) {
    // Step 1: JSON stringify with indentation (4 spaces)
    const first_pass = JSON.stringify(JSON.parse(ugly), null, 4)
    
    // Step 2: Put comma-sep. numbers on same line
    const comma_num_newline_ptn = /,\n +((\d\.)?\d+)/g
    const num_same_line = first_pass.replace(comma_num_newline_ptn, ', $1')
    
    // Step 3: Put flat arrays on same line
    const flat_array_ptn = /\[\n\s+(([\d.]+, )+[\d.]+)\n\s+\]/g
    return num_same_line.replace(flat_array_ptn, '[$1]')
}

/*
Before:
var ugly = `{"uuid": "5414681d-1b0c-439c-8d09-ca7c7a94e67e", "things": [{"ts": 1662050506431, "vectors": [[0.299479, 0.255556, 0.2, 0.075, 0.102], [0.511979, 0.081944, 0.051, 0.086, 0.129], [0.428125, 0.478241, 0.376, 0.369, 0.369]], "pick": [0, 1, 2]}, {"ts": 1662050569527, "vectors": [[0.511458, 0.080556, 0.051, 0.082, 0.133], [0.303646, 0.250926, 0.224, 0.094, 0.114], [0.509896, 0.352315, 0.384, 0.188, 0.22]], "pick": [1, 0, 2]}, {"ts": 1662050570559, "vectors": [[0.754167, 0.335185, 0.051, 0.086, 0.141], [0.519271, 0.065278, 0.161, 0.184, 0.247]], "pick": [2, 1]}]}`

After:
console.log(compactify(ugly))
{
    "uuid": "5414681d-1b0c-439c-8d09-ca7c7a94e67e",
    "things": [
        {
            "ts": 1662050506431,
            "vectors": [
                [0.299479, 0.255556, 0.2, 0.075, 0.102],
                [0.511979, 0.081944, 0.051, 0.086, 0.129],
                [0.428125, 0.478241, 0.376, 0.369, 0.369]
            ],
            "pick": [0, 1, 2]
        },
        {
            "ts": 1662050569527,
            "vectors": [
                [0.511458, 0.080556, 0.051, 0.082, 0.133],
                [0.303646, 0.250926, 0.224, 0.094, 0.114],
                [0.509896, 0.352315, 0.384, 0.188, 0.22]
            ],
            "pick": [1, 0, 2]
        },
        {
            "ts": 1662050570559,
            "vectors": [
                [0.754167, 0.335185, 0.051, 0.086, 0.141],
                [0.519271, 0.065278, 0.161, 0.184, 0.247]
            ],
            "pick": [2, 1]
        }
    ]
}
*/