用JSON值填充选择

Question

I have a function that gets a json text from a certain website:

window.onload = function httpGet()
{
    var xmlHttp = null;
    var box = document.getElementById("http") //just for testing
    xmlHttp = new XMLHttpRequest();
    xmlHttp.open( "GET", "http://link_to_Json_Text", false );
    xmlHttp.send( null );
    box.value += xmlHttp.responseText; //just for testing
    return xmlHttp.responseText.toJSON();

}

This dislays the results as:

    {
  "head": {
    "vars": [ "uri" , "label" ]
  } ,
  "results": {
    "bindings": [
      {
        "uri": { "type": "uri" , "value": "http://tematres.befdata.biow.uni-leipzig.de/vocab/?tema=751" } ,
        "label": { "type": "literal" , "xml:lang": "en" , "value": "15n" }
      } ,
      {

Then I perform this function to retrieve the values of the JSON as an object:

var results = httpGet().results.bindings.map(function(el){
    return { uri: el.uri.value, label: el.label.value };
});

Then I would like to get the values of the second function in an HTML select menu.

I am not sure however, if the second method is correctly calling the first one, because the console dislays errors like : Uncaught ReferenceError: httpGet is not defined

What I need is to use value from label to fill the select menu.

Answer 1

Just chain the success event for the request:

window.onload = function() //No function name needed
{
    var xmlHttp = null;
    var box = document.getElementById("http") //just for testing
    xmlHttp = new XMLHttpRequest();
    xmlHttp.open( "GET", "http://link_to_Json_Text", false );
    xmlHttp.send( null );
    xmlHttp.onreadystatechange=function()
    {
       if (xmlHttp.readyState==4 && xmlHttp.status==200)
       {
          var results =xmlHttp.responseText.toJSON();
          results.bindings.map(function(el){
              return { uri: el.uri.value, label: el.label.value };
          });
       }
    };
}

This just make the httpGet request and wait for the request to end (readyState ==4) to trigger the funcionality for the results process.

Anyway I would like to recomend you if you can, using jQuery because is so much simpler to work with Ajax than native JS