字符串去重 左右相邻除外 ，谁能优化一下代码

var a ='aabqaadaqqda'

var b =a.split('')

var c = []

for (var i =0;i

var upValue =''

  var nextValue =''

  var isSame =false

  var value =b[i]

if (i+1

nextValue =b[i+1]

}

if (i>0) {

upValue =b[i-1]

}

if (upValue ===value ||nextValue ===value) {

isSame =true

  }

var isHas =false

  var d =a.substring(0,i)

if (d.indexOf(value) != -1) {

isHas =true

  }

if (isSame ==true ||isHas ==false){

c.push(value)

}

}

console.log('=================',c.join(''))