JS一维数组转二维数组

var  json = [

                    {

                        school: "学院",

                        title: "数学",

                    },

                    {

                        school: "学院",

                        title: "数学",

                    },

                    {

                        school: "学院3",

                        title: "数学2",

                    },

                    {

                        school: "学院",

                        title: "数学3",

                    },

            ]

        //去重

            var newarr = json.filter((it, index)=>{

            var arrids = []

            json.forEach((item,i) => {

                arrids.push(item.title)

            })

            return arrids.indexOf(it.title) === index

            })  

                // console.log(arr2); 

            var lidev =[]

            var arr = []

            var cent =[]

               for(var i =0;i <newarr.length;i++){

                   var obj = {}

                    cent = []

                    for(var j =0;j <json.length;j++){

                        if(newarr[i].title === json[j].title){

                           cent.push( json[j])

                        }

                    }

                    obj.zy = cent

                    obj.title = newarr[i].title

                    arr.push({obj})

               }

            console.log(arr)

JS一维数组转二维数组