Function validateEasing

velocity.js:642–672

* Validate a easing option.

(value, duration, noError)

   * Validate a <code>easing</code> option.
   */
  function validateEasing(value, duration, noError) {
      if (isString(value)) {
          // Named easing
          return Easings[value];
      }
      if (isFunction(value)) {
          return value;
      }
      // TODO: We should only do these if the correct function exists - don't force loading.
      if (Array.isArray(value)) {
          if (value.length === 1) {
              // Steps
              return generateStep(value[0]);
          }
          if (value.length === 2) {
              // springRK4 must be passed the animation's duration.
              // Note: If the springRK4 array contains non-numbers,
              // generateSpringRK4() returns an easing function generated with
              // default tension and friction values.
              return generateSpringRK4(value[0], value[1], duration);
          }
          if (value.length === 4) {
              // Note: If the bezier array contains non-numbers, generateBezier()
              // returns undefined.
              return generateBezier.apply(null, value) || false;
          }
      }
      if (value != null && !noError) {
          console.error("VelocityJS: Trying to set 'easing' to an invalid value:", value);
      }
  }
  /**
   * Validate a <code>fpsLimit</code> option.
   */