角度源解码

Question

我是Angular和JavaScript的新手，无法解码下面的方法。你能帮我理解一下吗？

  getSalesgroupunitTx(): string {
    if (this . salesgroups !== undefined && this . salesgroupId !== undefined) {
      var salesgroup = this.salesgroups.filter((item, index) => {
        if (item.salesgroupId == this.salesgroupId) return true;
      });、
      this.salesgroupunitTx = salesgroup[0].salesgroupunitTx;
    }
    return this.salesgroupunitTx;

有一些材料......

构造函数中的

   this.salesGroupService
    .get()
    .then(outputJson => {
      this.working = false;
      console.log(JSON.stringify(outputJson));
      this.salesgroups = outputJson.salesgroups;
      this.salesgroupId = this.salesgroups[0]['salesgroupId'];

salesGroupService中的

。我从API服务器获得输入，如下所示

put(
    salesgroupId: number,
    salesgroupCd: string,
    salesgroupTx: string,
    salescategoryId: number,
    salesgroupunitTx: string,
    updprogramCd: string
  ): Promise<any> {
    const url = `${environment.baseUrl + this.apiUrl}/${salesgroupId}`;
    const jsonInput = {
      salesgroupCd: salesgroupCd,
      salesgroupTx: salesgroupTx,
      salescategoryId: salescategoryId,
      salesgroupunitTx: salesgroupunitTx,
      updprogramCd: updprogramCd
    };