pressure/src/helpers.js

Pressure is a lightweight JavaScript library for both Force Touch and 3D Touch through a single API.

//------------------- Helpers -------------------//

// accepts jQuery object, node list, string selector, then called a setup for each element
var loopPressureElements = function(selector, closure, options = {}) {
  // if a string is passed in as an element
  if(typeof selector === 'string' || selector instanceof String) {
    var elements = document.querySelectorAll(selector);
    for (var i = 0; i < elements.length; i++) {
      new Element(elements[i], closure, options);
    }
  // if a single element object is passed in
  } else if(isElement(selector)) {
    new Element(selector, closure, options);
  // if a node list is passed in ex. jQuery $() object
  } else {
    for (var i = 0; i < selector.length; i++) {
      new Element(selector[i], closure, options);
    }
  }
}

//Returns true if it is a DOM element
var isElement = function(o) {
  return (
    typeof HTMLElement === "object" ? o instanceof HTMLElement : //DOM2
    o && typeof o === "object" && o !== null && o.nodeType === 1 && typeof o.nodeName==="string"
  );
}

// the map method allows for interpolating a value from one range of values to another
// example from the Arduino documentation: https://www.arduino.cc/en/Reference/Map
var map = function(x, in_min, in_max, out_min, out_max) {
  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}

var supportsMouse            = false;
var supportsTouch            = false;
var supportsPointer          = false;
var supportsTouchForce       = false;
var supportsTouchForceChange = false;

if (typeof window !== 'undefined') {
  // only attempt to assign these in a browser environment.
  // on the server, this is a no-op, like the rest of the library
  if (typeof Touch !== 'undefined') {
    // In Android, new Touch requires arguments.
    try {
      if (Touch.prototype.hasOwnProperty('force') || 'force' in new Touch()) {
        supportsTouchForce = true;
      }
    } catch (e) {}
  }
  supportsTouch                   = 'ontouchstart'       in window.document && supportsTouchForce;
  supportsMouse                   = 'onmousemove'        in window.document && 'onwebkitmouseforcechanged' in window.document && !supportsTouch;
  supportsPointer                 = 'onpointermove'      in window.document;
  supportsTouchForceChange        = 'ontouchforcechange' in window.document;
}