Text var to json array

I'm trying to configure header bidding with prebid. I'm loading the ads that I want from database with php + mysql and I create a text variables in javascript with the data from php.

The problem comes when I have to create the variable "adUnits". If I create it manually writting it directly works fine but creating the same content with javascript I don't get it works.

This is the code that works

var adUnits = [{
     code: '/123/468x60',
     mediaTypes: {
         banner: {
             sizes: [
                 [468, 60]
             ]
         }
     },
     bids: [{
         bidder: 'adserver',
         params: {
             networkId: 1234
         }
     }]
 }, {
     code: '/123/336x280',
     mediaTypes: {
         banner: {
             sizes: [
                 [336, 280],
                 [300, 250]
             ]
         }
     },
     bids: [{
         bidder: 'adserver',
         params: {
             networkId: 1234
         }
     }]
 }, {
     code: '/123/300x600',
     mediaTypes: {
         banner: {
             sizes: [
                 [300, 600],
                 [300, 250]
             ]
         }
     },
     bids: [{
         bidder: 'adserver',
         params: {
             networkId: 1234
         }
     }]
 }];

This is the code that doesn't work

var arrayadsname = adsname.split('#');//content of arrayadsname => /123/468x60#/123/336x280#/123/300x600
var arrayadssize = adssize.split('#');//content of arrayadssize => 468x60#336,280|300,250#300,600|300,250
var arraysize = '';
var ad = '';
var adUnits = [];
var preadUnits = '';

for (var i = 0; i < arrayadsname.length; i++) {  
        var arraysizeparts = arrayadssize[i].split('|');

    for (var j = 0; j < arraysizeparts.length; j++) {
                if (j == 0){
                        arraysize = '[' + arraysizeparts[j] + ']';
                }else{
                        arraysize = arraysize + ',' + '[' + arraysizeparts[j] + ']';
                }
            }

        ad = '{code: \'' + arrayadsname[i] + '\', mediaTypes: {banner: {sizes: ' + '[' + arraysize + ']' + '}}, bids: [{bidder: \'adserver\', params: {networkId: 1234}}]}';

        if (i == 0) preadUnits = ad;
        else preadUnits = preadUnits + ',' + ad;
}
//Result of ad => {code: '/123/468x60', mediaTypes: {banner: {sizes: [[468,60]]}}, bids: [{bidder: 'adserver', params: {networkId: 1234}}]},{code: '/123/336x280', mediaTypes: {banner: {sizes: [[336,280],[300,250]]}}, bids: [{bidder: 'adserver', params: {networkId: 1234}}]},{code: '/123/300x600', mediaTypes: {banner: {sizes: [[300,600],[300,250]]}}, bids: [{bidder: 'adserver', params: {networkId: 1234}}]}


adUnits = "[" + JSON.stringify(preadUnits) + "]";

I've tried all posible combinations declare variable asUnits like object, array, text and using JSON.stringify, JSON.parse also declaring "arraysize" like array and parse it. I don't know which is the problem.

I see this error in console: "callee: [Exception: TypeError: 'caller', 'callee', and 'arguments' properties may not be accessed on strict mode functions or the arguments objects for calls to them at Arguments.invokeGetter"

Thanks in advance