Function checkDuplicateKeys

vue.js:8641–8659

(children)

        //检测key是否有重复
        function checkDuplicateKeys(children) {
            var seenKeys = {};
            for (var i = 0; i < children.length; i++) {  //循环子节点
                var vnode = children[i]; //获取子节点
                var key = vnode.key; //获取子节点的key
                if (isDef(key)) { //判断key是否有定义过
                    if (seenKeys[key]) { //如果定义过则发出警告
                        warn(
                            //检测到重复键:“+ key +”。这可能会导致更新错误。
                            ("Duplicate keys detected: '" + key + "'. This may cause an update error."),
                            vnode.context
                        );
                    } else {
                        //标志key 状态是 true
                        seenKeys[key] = true;
                    }
                }
            }
        }

        // 查找旧的vnode key
        function findIdxInOld(node, oldCh, start, end) {