text: /**
   * Created by Jonathan Zhang on 2017/5/19.
   */
  
  function sameSign(a,b) {
      return(a ^ b) >= 0
  }
  
  function vector(a,b) {
      return{
          x:b.x - a.x,
          y:b.y - a.y
      }
  }
  
  function vectorProduct(v1,v2) {
      return v1.x * v2.y - v2.x * v1.y
  }
  
  function isPointInTrangle(p,a,b,c) {
      var pa = vector(p, a);
      var pb = vector(p, b);
      var pc = vector(p, c);
  
      var t1 = vectorProduct(pa,pb);
      var t2 = vectorProduct(pb,pc);
      var t3 = vectorProduct(pc,pa);
  
      return sameSign(t1,t2) && sameSign(t2,t3)
  }
  
  function needDelay(elem, leftCorner, currMousePos) {
      var offset =elem.offset();
  
      var topLeft = {
          x: offset.left,
          y: offset.top
      }
  
      var bottomLeft ={
          x: offset.left,
          y: offset.top + elem.height()
      }
  
      return isPointInTrangle(currMousePos,leftCorner,topLeft,bottomLeft)
  }