Javascript prevent form submit when over limit

I follow the suggestion from Find size of file behind do开发者_JS百科wnload link with jQuery for the file size checking and added return false; to prevent form submission, but failed. The code as following:

 function findSize() {
  var fileInput = $("#loadfile")[0];
  if (fileInput.files[0].fileSize > 1048 ) {
    alert(fileInput.files[0].fileSize);
    return false;
  }
 }

<input type="submit" value="Submit" class="form-submit" onclick="findSize()" />

How do I prevent form submission when file size over limit?

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putting you check in the onsubmit of the form instead of the onclick of the submit-button should solve this.