Reworked to remove use of cached (potentially stale) style values. Fixes

 #404

changelog.md

@@ -1,6 +1,7 @@
 ## Changelog
 
 ##### v.6.0.0 - 2023-02-10
+* Reworked to remove use of cached (potentially stale) style values. Fixes #404
 * Dropped support for Internet Explorer
 
 ##### v.5.0.2 - 2022-11-20

dist/autosize.js

@@ -7,46 +7,7 @@
 
 	function assign(ta) {
 	  if (!ta || !ta.nodeName || ta.nodeName !== 'TEXTAREA' || assignedElements.has(ta)) return;
-	  var heightOffset = null;
-	  var clientWidth = null;
-	  var cachedHeight = null;
-
-	  function init() {
-	    var style = window.getComputedStyle(ta);
-
-	    if (style.resize === 'vertical') {
-	      ta.style.resize = 'none';
-	    } else if (style.resize === 'both') {
-	      ta.style.resize = 'horizontal';
-	    }
-
-	    if (style.boxSizing === 'content-box') {
-	      heightOffset = -(parseFloat(style.paddingTop) + parseFloat(style.paddingBottom));
-	    } else {
-	      heightOffset = parseFloat(style.borderTopWidth) + parseFloat(style.borderBottomWidth);
-	    } // Fix when a textarea is not on document body and heightOffset is Not a Number
-
-
-	    if (isNaN(heightOffset)) {
-	      heightOffset = 0;
-	    }
-
-	    update();
-	  }
-
-	  function changeOverflow(value) {
-	    {
-	      // Chrome/Safari-specific fix:
-	      // When the textarea y-overflow is hidden, Chrome/Safari do not reflow the text to account for the space
-	      // made available by removing the scrollbar. The following forces the necessary text reflow.
-	      var width = ta.style.width;
-	      ta.style.width = '0px'; // Force reflow:
-	      /* jshint ignore:end */
-
-	      ta.style.width = width;
-	    }
-	    ta.style.overflowY = value;
-	  }
+	  var previousHeight = null;
 
 	  function cacheScrollTops(el) {
 	    var arr = [];
@@ -70,78 +31,99 @@
 	    };
 	  }
 
-	  function resize() {
+	  var computed = window.getComputedStyle(ta);
+
+	  function update(cachedTextAlign) {
+	    if (cachedTextAlign === void 0) {
+	      cachedTextAlign = null;
+	    }
+
+	    var initialOverflowY = computed.overflowY;
+
 	    if (ta.scrollHeight === 0) {
 	      // If the scrollHeight is 0, then the element probably has display:none or is detached from the DOM.
 	      return;
 	    } // ensure the scrollTop values of parent elements are not modified as a consequence of calculating the textarea height
 
 
 	    var restoreScrollTops = cacheScrollTops(ta);
-	    ta.style.height = ''; // this is necessary for getting an accurate scrollHeight on the next line
+	    ta.style.height = ''; // this is necessary for to scrollHeight to accurately reflect situations where the textarea should shrink
+	    // disallow vertical resizing
 
-	    ta.style.height = ta.scrollHeight + heightOffset + 'px'; // used to check if an update is actually necessary on window.resize
+	    if (computed.resize === 'vertical') {
+	      ta.style.resize = 'none';
+	    } else if (computed.resize === 'both') {
+	      ta.style.resize = 'horizontal';
+	    }
 
-	    clientWidth = ta.clientWidth;
-	    restoreScrollTops();
-	  }
+	    var newHeight;
 
-	  function update() {
-	    resize();
-	    var styleHeight = parseFloat(ta.style.height);
-	    var computed = window.getComputedStyle(ta);
-	    var actualHeight = parseFloat(computed.height); // The actual height not matching the style height (set via the resize method) indicates that
-	    // the max-height has been exceeded, in which case the overflow should be allowed.
+	    if (computed.boxSizing === 'content-box') {
+	      newHeight = ta.scrollHeight - (parseFloat(computed.paddingTop) + parseFloat(computed.paddingBottom));
+	    } else {
+	      newHeight = ta.scrollHeight + parseFloat(computed.borderTopWidth) + parseFloat(computed.borderBottomWidth);
+	    }
 
-	    if (actualHeight < styleHeight) {
+	    if (computed.maxHeight !== 'none' && newHeight > parseFloat(computed.maxHeight)) {
 	      if (computed.overflowY === 'hidden') {
-	        changeOverflow('scroll');
-	        resize();
-	        actualHeight = parseFloat(window.getComputedStyle(ta).height);
-	      }
-	    } else {
-	      // Normally keep overflow set to hidden, to avoid flash of scrollbar as the textarea expands.
-	      if (computed.overflowY !== 'hidden') {
-	        changeOverflow('hidden');
-	        resize();
-	        actualHeight = parseFloat(window.getComputedStyle(ta).height);
+	        ta.style.overflow = 'scroll';
 	      }
+
+	      newHeight = parseFloat(computed.maxHeight);
+	    } else if (computed.overflowY !== 'hidden') {
+	      ta.style.overflow = 'hidden';
+	    }
+
+	    ta.style.height = newHeight + 'px';
+
+	    if (cachedTextAlign) {
+	      ta.style.textAlign = cachedTextAlign;
 	    }
 
-	    if (cachedHeight !== actualHeight) {
-	      cachedHeight = actualHeight;
+	    restoreScrollTops();
+
+	    if (previousHeight !== newHeight) {
 	      ta.dispatchEvent(new Event('autosize:resized', {
 	        bubbles: true
 	      }));
+	      previousHeight = newHeight;
 	    }
-	  }
 
-	  var pageResize = function pageResize() {
-	    if (ta.clientWidth !== clientWidth) {
-	      update();
+	    if (initialOverflowY !== computed.overflow && !cachedTextAlign) {
+	      var textAlign = computed.textAlign;
+
+	      if (computed.overflow === 'hidden') {
+	        // Webkit fails to reflow text after overflow is hidden,
+	        // even if hiding overflow would allow text to fit more compactly.
+	        // The following is intended to force the necessary text reflow.
+	        ta.style.textAlign = textAlign === 'start' ? 'end' : 'start';
+	      }
+
+	      update(textAlign);
 	    }
-	  };
+	  }
 
 	  var destroy = function (style) {
-	    window.removeEventListener('resize', pageResize, false);
+	    window.removeEventListener('resize', update, false);
 	    ta.removeEventListener('input', update, false);
 	    ta.removeEventListener('keyup', update, false);
 	    ta.removeEventListener('autosize:destroy', destroy, false);
 	    ta.removeEventListener('autosize:update', update, false);
 	    Object.keys(style).forEach(function (key) {
-	      ta.style[key] = style[key];
+	      return ta.style[key] = style[key];
 	    });
 	    assignedElements["delete"](ta);
 	  }.bind(ta, {
 	    height: ta.style.height,
 	    resize: ta.style.resize,
+	    textAlign: ta.style.textAlign,
 	    overflowY: ta.style.overflowY,
 	    overflowX: ta.style.overflowX,
 	    wordWrap: ta.style.wordWrap
 	  });
 
 	  ta.addEventListener('autosize:destroy', destroy, false);
-	  window.addEventListener('resize', pageResize, false);
+	  window.addEventListener('resize', update, false);
 	  ta.addEventListener('input', update, false);
 	  ta.addEventListener('autosize:update', update, false);
 	  ta.style.overflowX = 'hidden';
@@ -150,7 +132,7 @@
 	    destroy: destroy,
 	    update: update
 	  });
-	  init();
+	  update();
 	}
 
 	function destroy(ta) {