Function createKeyToOldIdx

vue.js:7913–7923

(children, beginIdx, endIdx)

    // 创建key 如果没有key 则用索引作为key
    function createKeyToOldIdx(children, beginIdx, endIdx) {
        var i, key;
        var map = {};
        for (i = beginIdx; i <= endIdx; ++i) {
            key = children[i].key;
            if (isDef(key)) {
                map[key] = i;
            }
        }
        return map
    }

    //创建虚拟dom
    function createPatchFunction(backend) {