var data = "1,menu1,3000\n\

2,menu1_1,5000\n\

2,menu1_2,6000\n\

2,menu1_3,7000\n\

1,menu2,8000\n\

2,menu2_1,5000\n\

3,menu2_1_1,5000\n\

3,menu2_1_2,7000\n\

2,menu2_2,6000\n\

2,menu2_3,7000\n\

1,menu3,9000\n\

1,menu4,10000"

​

var array = data.split("\n").map(function(row, index) { 

  var arr = row.split(",")

  return {

    id: index+1,

    level: +arr[0],

    label: arr[1],

    price: arr[2],

    children: []

  }

})

​

array.unshift({ level: 0, children: [] })

var parents = array.slice(0,1)

​

for(var i=1; i<array.length; i++) {

  var prev = array[i-1]

  var obj = array[i]

  var p = parents[parents.length-1]

  if(obj.level > prev.level) {

    parents.push(prev)

    p = prev

  } else if (obj.level < prev.level) {

    do {

      p = parents.pop()

    } while(obj.level < p.level)

    p = parents[parents.length-1]

  }

  p.children.push(obj)

}

​

var result = parents[0].children

​

console.log(result)