phpjs/experimental/filesystem/ftell.js

php.js offers community built php functions in javascript

function ftell(handle) {
  // http://kevin.vanzonneveld.net
  // +   original by: Brett Zamir (http://brett-zamir.me)
  // *     example 1: var h = fopen('http://kevin.vanzonneveld.net/pj_test_supportfile_1.htm', 'r');
  // *     example 1: fread(h, 100);
  // *     example 1: ftell(h);
  // *     returns 1: 99

  var getFuncName = function(fn) {
    var name = (/\W*function\s+([\w\$]+)\s*\(/).exec(fn);
    if (!name) {
      return '(Anonymous)';
    }
    return name[1];
  };
  if (!this.php_js || !this.php_js.resourceData || !this.php_js.resourceDataPointer || !handle || !handle.constructor || getFuncName(handle.constructor) !== 'PHPJS_Resource') {
    return false;
  }
  return this.php_js.resourceDataPointer[handle.id] * 2 - 1; // We're currently storing by character, so need to multiply by two; subtract one to appear like array pointer
}