textarea根据内容自适应高度

    makeExpandingArea(el) {
      var setStyle = function(el) {
        el.style.height = \"auto\";
        el.style.height = el.scrollHeight + \"px\";
        // console.log(el.scrollHeight);
      };
      var delayedResize = function(el) {
        window.setTimeout(function() {
          setStyle(el);
        }, 0);
      };
      if (el.addEventListener) {
        el.addEventListener(
          \"input\",
          function() {
            setStyle(el);
          },
          false
        );
        setStyle(el);
      } else if (el.attachEvent) {
        el.attachEvent(\" \", function() {
          setStyle(el);
        });
        setStyle(el);
      }
      if (window.VBArray && window.addEventListener) {
        //IE9
        el.attachEvent(\" \", function() {
          var key = window.event.keyCode;
          if (key == 8 || key == 46) delayedResize(el);
        });
        el.attachEvent(\" \", function() {
          delayedResize(el);
        }); //处理粘贴
      }
    }