google.setOnLoadCallback not able to get the document elements

问题

I am trying to get some graph functionalities with corechart using JQuery but I am not able to get any document elements once the visualization APIs are loaded. Below is my sample example:

$(document).ready(function() {
  if ($("#myId").length > 0) { 
    google.load("visualization", "1.1", {
      packages: ["corechart"]
    });
    google.setOnLoadCallback(function() {
      if ($("#myId").length > 0) {
        alert("Found a match!!");
      }else{
        alert("Not found!!");
      }
    });
  }
});

<html>

  <head>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script>
    <link rel="stylesheet" href="style.css" />
    <script src="script.js"></script>
    <script type="text/javascript" src="https://www.google.com/jsapi"></script>
  </head>

  <body>
    <h1>Hello Plunker!</h1>
    <div id="myId">Hello from Div!!</div>
  </body>

</html>

I want the alert in my if block to be executed. I am loading the visualization packages only after the check for #myId but its lost(rather all the html elements) in the call back. Please advice

回答1:

I think it may have something to do with setOnLoadCallback.
However, you can add a reference to the callback in the load statement.

$(document).ready(function(){
  if ($("#myId").length > 0) {
    google.load('visualization', '1', {
      'packages': ['corechart'],
      'callback': function(){
        if ($("#myId").length > 0) {
          alert("Found a match!!");
        }else{
          alert("Not found!!");
        }
      }
    });    
  }
});

<html>
  <head>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script>
    <link rel="stylesheet" href="style.css" />
    <script src="script.js"></script>
    <script type="text/javascript" src="https://www.google.com/jsapi"></script>
  </head>

  <body>
    <h1>Hello Plunker!</h1>
    <div id="myId">Hello from Div!!</div>
  </body>

</html>

I think setOnLoadCallback pulls double duty and not only waits for google.load...
but also the document
since document has already been loaded, maybe something gets fouled up...

来源：https://stackoverflow.com/questions/35304392/google-setonloadcallback-not-able-to-get-the-document-elements

标签

jquery

charts

google-visualization