getDataGradually

gistfile1.js

function getDataGradually(data, childKey, gap, count, updateCb, finishCb) {
  const lastPositon = [];
  const linearData = [];
  const ret = [];


  function getLinearData(arr, position) {
      arr.forEach(function (obj, index) {
          const pos = position.concat([index]);
          if (obj[childKey] && obj[childKey].length) {
              var children = obj[childKey];
              obj[childKey] = [];
              linearData.push({
                  obj,
                  pos
              });
              getLinearData(children, pos);
          } else {
              linearData.push({
                  obj,
                  pos
              });
          }
      });
  }
  getLinearData(data, []);

  function insertData({
      obj,
      pos
  }) {

      let target = ret;
      pos.forEach(function (i, index) {


          if (index === pos.length - 1) {
              target[i] = obj;

          } else {
              target = target[i][childKey];
          }
      });

  }
            let handled = 0;

            function doInsert() {
                let start = handled;
                let end;
                if (handled + count > linearData.length) {
                    end = linearData.length;
                } else {
                    end = handled + count;
                }
                for (let i = start; i < end; i++) {
                    insertData(linearData[i]);
                }
                handled += count;
                if (handled < linearData.length) {
                    setTimeout(function () {
                        doInsert();
                        updateCb && updateCb();
                    }, gap);
                } else {
                    finishCb && finishCb();
                }
            }
            doInsert();



            return ret;
        }