mounted () {
    function main(ta) {

      if (!ta || !ta.nodeName || ta.nodeName !== 'TEXTAREA' || ta.hasAttribute('data-autosize-on')) { return; }

      var maxHeight;
      var heightOffset;

      function init() {
        var style = window.getComputedStyle(ta, null);

        if (style.resize === 'vertical') {
          ta.style.resize = 'none';
        } else if (style.resize === 'both') {
          ta.style.resize = 'horizontal';
        }

        // horizontal overflow is hidden, so break-word is necessary for handling words longer than the textarea width
        ta.style.wordWrap = 'break-word';

        // Chrome/Safari-specific fix:
        // When the textarea y-overflow is hidden, Chrome/Safari doesn't reflow the text to account for the space
        // made available by removing the scrollbar. This workaround will cause the text to reflow.
        var width = ta.style.width;
        ta.style.width = '0px';
        // Force reflow:
        /* jshint ignore:start */
        ta.offsetWidth;
        /* jshint ignore:end */
        ta.style.width = width;

        maxHeight = style.maxHeight !== 'none' ? parseFloat(style.maxHeight) : false;

        if (style.boxSizing === 'content-box') {
          heightOffset = -(parseFloat(style.paddingTop)+parseFloat(style.paddingBottom));
        } else {
          heightOffset = parseFloat(style.borderTopWidth)+parseFloat(style.borderBottomWidth);
        }

        adjust();
      }

      function adjust() {
        var startHeight = ta.style.height;
        var htmlTop = document.documentElement.scrollTop;
        var bodyTop = document.body.scrollTop;

        ta.style.height = 'auto';

        var endHeight = ta.scrollHeight+heightOffset;

        if (maxHeight !== false && maxHeight < endHeight) {
          endHeight = maxHeight;
          if (ta.style.overflowY !== 'scroll') {
            ta.style.overflowY = 'scroll';
          }
        } else if (ta.style.overflowY !== 'hidden') {
          ta.style.overflowY = 'hidden';
        }

        ta.style.height = endHeight+'px';

        // prevents scroll-position jumping
        document.documentElement.scrollTop = htmlTop;
        document.body.scrollTop = bodyTop;

        if (startHeight !== ta.style.height) {
          var evt = document.createEvent('Event');
          evt.initEvent('autosize.resized', true, false);
          ta.dispatchEvent(evt);
        }
      }

      // IE9 does not fire onpropertychange or oninput for deletions,
      // so binding to onkeyup to catch most of those events.
      // There is no way that I know of to detect something like 'cut' in IE9.
      if ('onpropertychange' in ta && 'oninput' in ta) {
        ta.addEventListener('keyup', adjust);
      }

      window.addEventListener('resize', adjust);
      ta.addEventListener('input', adjust);

      ta.addEventListener('autosize.update', adjust);

      ta.addEventListener('autosize.destroy', function(style){
        window.removeEventListener('resize', adjust);
        ta.removeEventListener('input', adjust);
        ta.removeEventListener('keyup', adjust);
        ta.removeEventListener('autosize.destroy');

        Object.keys(style).forEach(function(key){
          ta.style[key] = style[key];
        });

        ta.removeAttribute('data-autosize-on');
      }.bind(ta, {
        height: ta.style.height,
        overflow: ta.style.overflow,
        overflowY: ta.style.overflowY,
        wordWrap: ta.style.wordWrap,
        resize: ta.style.resize
      }));

      ta.setAttribute('data-autosize-on', true);
      ta.style.overflow = 'hidden';
      ta.style.overflowY = 'hidden';

      init();
    }
    main(this.$refs.textarea)
  }

1.js

var elements=document.querySelectorAll('textarea')
if (elements && elements.length) {
  Array.prototype.forEach.call(elements, main);
} else if (elements && elements.nodeName) {

  main(elements);
}

2.vue (像这种找不到dom的)

image.png

 main(this.$refs.textarea)