Unexpected token < in JSON at position 4 - when fetch link Ajax [GAS] - json

Question

First, I have to apologize for my poor English skill I am using Google Apps Script.
I'm trying to get JSON data from AJAX link but sometimes error occurs
Unexpected token < in JSON at position 4
I know the problem here is the data return form "HTML" while i expect "JSON"
I trying
My Script
async function getJSON () {
const myHeaders = {
'cache' : 'no-cache',
'pragma': 'no-cache',
'Cache-Control': 'no-cache',
'accept': 'text',
'dataType' : 'text',
'contentType': 'application/json; charset=utf-8',
};
const myInit = {
muteHttpExceptions: true,
method: 'GET',
headers: myHeaders,
};
const url = "https://www.xxxx.xxx/xxxxxxx/?ajax=xxxxxxx"
const content = await UrlFetchApp.fetch(url ,myInit).getContentText();
const obj = JSON.parse(content);
....
...
}

Answer 1

The problem as you say is that sometimes the response is an HTML, which generates that when the JSON.parse function is called, an error arises because the response does not contain a valid JSON.
This error comes from the server, so there is not much you can do about it. One way to handle the error is with a try-catch block, which is common practice in asynchronous fetch.
For example:
async function getJSON() {
try {
const myHeaders = {
'cache': 'no-cache',
'pragma': 'no-cache',
'Cache-Control': 'no-cache',
'accept': 'text',
'dataType': 'text',
'contentType': 'application/json; charset=utf-8',
};
const myInit = {
muteHttpExceptions: true,
method: 'GET',
headers: myHeaders,
};
const url = "https://www.xxxx.xxx/xxxxxxx/?ajax=xxxxxxx"
const content = await UrlFetchApp.fetch(url, myInit).getContentText();
const obj = JSON.parse(content);
// ...
} catch (err) {
console.log({
err
})
}
}