两个百位以上的数 相加

                                addBigNum(a, b){
				  let arrA = a.split('').reverse()
				  let arrB = b.split('').reverse()
				  let aLen = arrA.length
				  let bLen = arrB.length
				  let shortArr, shortLen, longArr, longLen
				  let result = []
				  if(aLen<bLen){
				    shortArr = arrA
				    shortLen = aLen
				    longArr = arrB
				    longLen = bLen
				  }else {
				    shortArr = arrB
				    shortLen = bLen
				    longArr = arrA
				    longLen = aLen
				  }
				  let add = 0
				  for(let i = 0; i < shortLen; i++){
				    let temp = (parseInt(arrA[i])+parseInt(arrB[i])+add)%10
				    result.push(temp)
				    add = Math.floor((parseInt(arrA[i])+parseInt(arrB[i])+add)/10)
				  }
				  if(shortLen===longLen){
				    result.push(add)
				  }else{
				    for(let j = shortLen; j < longLen; j++){
				      if(j===longLen-1){
				        result.push(parseInt(longArr[j])+add)
				      }else{
				        let temp = (parseInt(longArr[j])+add)%10
				        result.push(temp)
				        add = Math.floor((parseInt(longArr[j])+add)/10)
				      }
				    }
				  }
				  return result.reverse().join('')
				}