It sounds like you're retrieving a JSON string in JavaScript (perhaps via AJAX?). If you need to make this into an actual array value, you'd probably want to use JSON.parse().

var retrievedJSON = '["float","float","float","float"]'; // normally from AJAX
var myArray = JSON.parse(retrievedJSON);

If you're actually writing out a value into the page, rather than using AJAX, then you should be able to simply echo the output of json_encode directly, without quoting; JSON itself is valid JavaScript.

var myArray = <?php echo json_encode($myPhpArray); ?>;

You want to json_encode($json, JSON_FORCE_OBJECT).

The JSON_FORCE_OBJECT flag, as the name implies, forces the json output to be an object, even when it otherwise would normally be represented as an array.

You can also eliminate the use of array_push for some slightly cleaner code:

$json[] = ['ip' => $ip, 'port' => $port];

First you need a PHP file on a Apache server somewhere with PHP installed. Make a file like this:

localhost:8888/myfile.php

<?php
    $arr = array ('a'=>1,'b'=>2,'c'=>3,'d'=>4,'e'=>5);

    echo json_encode($arr); // {"a":1,"b":2,"c":3,"d":4,"e":5}
?>

Then your JavaScript (in this example I use jQuery):

$.getJSON('http://localhost:8888/myfile.php', function(data) {
    console.log(data);
});

This should be a start to get PHP arrays in to your JavaScript.