start: function start()

in assets/js/vue.js [9727:9812]
72 lines of code
19 McCabe index (conditional complexity)

      start: function start (tag, attrs, unary, start$1, end) {
        // 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 = createASTElement(tag, attrs, currentParent);
        if (ns) {
          element.ns = ns;
        }

        {
          if (options.outputSourceRange) {
            element.start = start$1;
            element.end = end;
            element.rawAttrsMap = element.attrsList.reduce(function (cumulated, attr) {
              cumulated[attr.name] = attr;
              return cumulated
            }, {});
          }
          attrs.forEach(function (attr) {
            if (invalidAttributeRE.test(attr.name)) {
              warn$2(
                "Invalid dynamic argument expression: attribute names cannot contain " +
                "spaces, quotes, <, >, / or =.",
                {
                  start: attr.start + attr.name.indexOf("["),
                  end: attr.start + attr.name.length
                }
              );
            }
          });
        }

        if (isForbiddenTag(element) && !isServerRendering()) {
          element.forbidden = true;
          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.',
            { start: element.start }
          );
        }

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

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

        if (!root) {
          root = element;
          {
            checkRootConstraints(root);
          }
        }

        if (!unary) {
          currentParent = element;
          stack.push(element);
        } else {
          closeElement(element);
        }
      },