Update Database Using JavaScript in HTML form

I think this is a simple question, but I'm new to node.js and HTML. I have a simple index.html form with 2 input fields (ID and Amount). I want to update my dynamoDB table - record of the unique ID, deducting the input amount value of the form from the dynamoDB table "balance". I have a get and put API that works in POSTMAN, I'm just not clear how to call the PUT from within the portion of the HTML. I think I am over-engineering because I cannot find the simple 'update' syntax to use. Any useful feedback would be appreciated!

GET API endpoint = 'url'/ PUT API endpoint = 'url'/

This is a sample snippet I've been trying and receiving the below error

  var inputClient = fetch(API_ENDPOINT +'/' +clientId).
    then(response => {
      response.json().then(json => {
          'clientName: ${json.results[0].clientName} - ',
          'clientBalance: ${json.results[0].clientBalance} -',
          'clientRetainer: ${json.results[0].clientRetainer}'
    .catch(error => {

Failed to load https://...api/submitPayment/ : No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'https://s3.amazonaws.com' is therefore not allowed access. The response had HTTP status code 403. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled. index.html:87 TypeError: Failed to fetch

I have set the Access-Control-Allow_Origin header

console.log("Access Control Header Present? : " + JSON.stringify(headers1)); 

Access Control Header Present? : {"Access-Control-Allow-Origin":"*","Content-type":"application/json"}