Function parseArg

www/js/ext/component.js:663–677

(componentEl, prop)

      return source;
    }
    function parseArg(componentEl, prop) {
      if (typeof prop !== "string") return null;
      var cache = componentEl._attrsCache || (componentEl._attrsCache = {});
      if (!cache[prop]) {
        var attrValue = componentEl.getAttribute(prop);
        if (attrValue == null) return null;
        try {
          cache[prop] = createParser(tokenizer.tokenize(attrValue)).requireElement("expression");
        } catch (e) {
          console.error("component: failed to parse attrs." + prop + ":", e.message);
          return null;
        }
      }
      return cache[prop];
    }
    function parentContext(componentEl) {
      var parent = componentEl.parentElement;
      return parent ? runtime.makeContext(parent, null, parent, null) : null;