Function once

MathBox/mathbox-bundle.js:40726–40744

* Creates a function that is restricted to execute `func` once. Repeat calls to * the function will return the value of the first call. The `func` is executed * with the `this` binding of the created function. * * @static * @memberOf _ * @category Functions * @para

(func)

     * // `initialize` executes `createApplication` once
     */
    function once(func) {
      var ran,
          result;

      if (!isFunction(func)) {
        throw new TypeError;
      }
      return function() {
        if (ran) {
          return result;
        }
        ran = true;
        result = func.apply(this, arguments);

        // clear the `func` variable so the function may be garbage collected
        func = null;
        return result;
      };
    }

    /**
     * Creates a function that, when called, invokes `func` with any additional