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 判断数组里面是否有这个值，返回这个值的索引
let arr = [ 2, 4, 6, 7, 12];
  let queen = (temp)=> {
      let int = -1;
      arr.forEach( (item, index)=> {
          if(temp == item){
              int = index
              return int;
          } else {
              return int
          }
      })
      return int
  }
console.log(queen(12)) // 4