A strange issue with ajax: SyntaxError occurs with an unexpected token "if"

Having an issue with my javascript code:

function updatePage() {   
if (request.readyState == 4)
    if (request.status == 200)
        var data = JSON.parse(request.responseText);
        update_select($('select[name=island_name]'), data);
    else if (request.status == 404)
        alert("Request url does not exist");
    else
        alert("Error: status code is " + request.status);
}

I'm consistently encountering an 

Uncaught SyntaxError: Unexpected token if
error that stops the execution of my script. Any suggestions on how to resolve this?

javascriptajax

Answer №1

There seems to be a problem with the code you provided - it is missing some curly braces in the update_select() line causing issues. Although these braces are not always necessary, since you want to execute two statements within the first if() condition, it's crucial to include them. It would be best to add the braces in all instances for clarity.

function updatePage() {   
  if (request.readyState == 4) {
    if (request.status == 200) {
        var data = JSON.parse(request.responseText);
        // Make sure to use {} on this block as the second statement is executed after the if()
        update_select($('select[name=island_name]'), data);
    }
    else if (request.status == 404) {
        alert("The requested URL does not exist");
    }
    else {
        alert("An error occurred: status code is " + request.status);
    }
  }
}

Answer №2

function processResponse() {   
if (response.ready == 2)
    if (response.success == 500)
    {
        var info = JSON.parse(response.dataReceived);
        update_selector($('select[name=island_name]'), info);
    }
    else if (response.success == 404)
        alert("Oops, that request URL is not valid");
    else
        alert("Uh-oh: the status code returned is " + response.success);
}

You correctly indented line 6 (update_selector...), but it should not have been inside the if block.

Answer №3

You need to add the missing curly bracket { at line 2 and 3:

function updatePage() {   
   if (request.readyState == 4) {
      if (request.status == 200) {
          var data = JSON.parse(request.responseText);
          update_select($('select[name=island_name]'), data);
      }
      else if (request.status == 404)
         alert("Request url does not exist");
      else
        alert("Error: status code is " + request.status);
    }
}

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