数组合并成一个前,一个后的样子?

Question

        let a = [
          ["1995-09-01"],
          ["1998-09-01"],
          ["2001-09-01"],
          ["2003-08-01"],
          ["2004-01-01"],
          ["2008-07-01"],
          ["2009-03-01"],
          ["2010-07-01"],
          ["2014-07-01"],
          ["2015-01-01"],
          ["2021-10-27"]
        ]
        let b = [
          ["1998-07-31"],
          ["2001-07-31"],
          ["2003-07-31"],
          ["2008-06-30"],
          ["2007-01-01"],
          ["2009-02-28"],
          ["2010-06-30"],
          ["2014-06-30"],
          ["2021-10-27"],
          ["2020-01-01"],
          ["2021-10-27"]
        ]

怎么合并成这种一前一后的样子:

Answer 1

   let a = [
      ["1995-09-01"],
      ["1998-09-01"],
      ["2001-09-01"],
      ["2003-08-01"],
      ["2004-01-01"],
      ["2008-07-01"],
      ["2009-03-01"],
      ["2010-07-01"],
      ["2014-07-01"],
      ["2015-01-01"],
      ["2021-10-27"],
    ];
    let b = [
      ["1998-07-31"],
      ["2001-07-31"],
      ["2003-07-31"],
      ["2008-06-30"],
      ["2007-01-01"],
      ["2009-02-28"],
      ["2010-06-30"],
      ["2014-06-30"],
      ["2021-10-27"],
      ["2020-01-01"],
      ["2021-10-27"],
    ];
    a.forEach((item,index) => {
      console.log([...item, ...b[index]]);
    })