start: function start()

in web-ui/src/js/vue.js [8001:8126]

• 44 lines of code
• 21 McCabe index (conditional complexity)

    start: function start (tag, attrs, unary) {
      // check namespace.
      // inherit parent ns if there is one
      var ns = (currentParent && currentParent.ns) || platformGetTagNamespace(tag);

      // handle IE svg bug
      /* istanbul ignore if */
      if (isIE && ns === 'svg') {
        attrs = guardIESVGBug(attrs);
      }

      var element = {
        type: 1,
        tag: tag,
        attrsList: attrs,
        attrsMap: makeAttrsMap(attrs),
        parent: currentParent,
        children: []
      };
      if (ns) {
        element.ns = ns;
      }

      if (isForbiddenTag(element) && !isServerRendering()) {
        element.forbidden = true;
        "development" !== 'production' && warn$2(
          'Templates should only be responsible for mapping the state to the ' +
          'UI. Avoid placing tags with side-effects in your templates, such as ' +
          "<" + tag + ">" + ', as they will not be parsed.'
        );
      }

      // apply pre-transforms
      for (var i = 0; i < preTransforms.length; i++) {
        preTransforms[i](element, options);
      }

      if (!inVPre) {
        processPre(element);
        if (element.pre) {
          inVPre = true;
        }
      }
      if (platformIsPreTag(element.tag)) {
        inPre = true;
      }
      if (inVPre) {
        processRawAttrs(element);
      } else {
        processFor(element);
        processIf(element);
        processOnce(element);
        processKey(element);

        // determine whether this is a plain element after
        // removing structural attributes
        element.plain = !element.key && !attrs.length;

        processRef(element);
        processSlot(element);
        processComponent(element);
        for (var i$1 = 0; i$1 < transforms.length; i$1++) {
          transforms[i$1](element, options);
        }
        processAttrs(element);
      }

      function checkRootConstraints (el) {
        {
          if (el.tag === 'slot' || el.tag === 'template') {
            warnOnce(
              "Cannot use <" + (el.tag) + "> as component root element because it may " +
              'contain multiple nodes.'
            );
          }
          if (el.attrsMap.hasOwnProperty('v-for')) {
            warnOnce(
              'Cannot use v-for on stateful component root element because ' +
              'it renders multiple elements.'
            );
          }
        }
      }

      // tree management
      if (!root) {
        root = element;
        checkRootConstraints(root);
      } else if (!stack.length) {
        // allow root elements with v-if, v-else-if and v-else
        if (root.if && (element.elseif || element.else)) {
          checkRootConstraints(element);
          addIfCondition(root, {
            exp: element.elseif,
            block: element
          });
        } else {
          warnOnce(
            "Component template should contain exactly one root element. " +
            "If you are using v-if on multiple elements, " +
            "use v-else-if to chain them instead."
          );
        }
      }
      if (currentParent && !element.forbidden) {
        if (element.elseif || element.else) {
          processIfConditions(element, currentParent);
        } else if (element.slotScope) { // scoped slot
          currentParent.plain = false;
          var name = element.slotTarget || '"default"';(currentParent.scopedSlots || (currentParent.scopedSlots = {}))[name] = element;
        } else {
          currentParent.children.push(element);
          element.parent = currentParent;
        }
      }
      if (!unary) {
        currentParent = element;
        stack.push(element);
      } else {
        endPre(element);
      }
      // apply post-transforms
      for (var i$2 = 0; i$2 < postTransforms.length; i$2++) {
        postTransforms[i$2](element, options);
      }
    },