一维数组转二维数组

在项目上，会遇到将一个一维数组的数据，按板块的分布排版这一类的需求。这种需求的数据往往就是数组元素中含有相同字段，以这相同字段分类即可达到需求。

以以下数据为例：

将

let oldArr= [ { name: "一级光圆钢", type: "热轧光圆钢筋（盘卷）", material: "HPB300", specification: "Φ8", }, { name: "一级光圆钢", type: "热轧光圆钢筋（盘卷）", material: "HPB300", specification: "Φ10", }, { name: "一级光圆钢", type: "热轧光圆钢筋（盘卷）", material: "HPB300", specification: "Φ12", }, { name: "四级抗震螺纹钢", type: "热轧带肋钢筋", material: "HRB500E", specification: "Φ14-普尺", }, { name: "四级抗震螺纹钢", type: "热轧带肋钢筋", material: "HRB500E", specification: "Φ16-L12M", }, { name: "三级抗震螺纹钢", type: "热轧带肋钢筋", material: "HRB400E", specification: "Φ20-L12M", }, { name: "三级抗震螺纹钢", type: "热轧带肋钢筋", material: "HRB400E", specification: "Φ20-L9M", }, { name: "三级抗震螺纹钢", type: "热轧带肋钢筋（盘卷）", material: "HRB400E", specification: "Φ10", }, { name: "三级抗震螺纹钢", type: "热轧带肋钢筋（盘卷）", material: "HRB400E", specification: "Φ12", }, ];

转换为

let newArr= [ [ { name: "一级光圆钢", type: "热轧光圆钢筋（盘卷）", material: "HPB300", specification: "Φ8", }, { name: "一级光圆钢", type: "热轧光圆钢筋（盘卷）", material: "HPB300", specification: "Φ10", }, { name: "一级光圆钢", type: "热轧光圆钢筋（盘卷）", material: "HPB300", specification: "Φ12", }, ], [ { name: "四级抗震螺纹钢", type: "热轧带肋钢筋", material: "HRB500E", specification: "Φ14-普尺", }, { name: "四级抗震螺纹钢", type: "热轧带肋钢筋", material: "HRB500E", specification: "Φ16-L12M", }, ], [ { name: "三级抗震螺纹钢", type: "热轧带肋钢筋", material: "HRB400E", specification: "Φ20-L12M", }, { name: "三级抗震螺纹钢", type: "热轧带肋钢筋", material: "HRB400E", specification: "Φ20-L9M", }, ], [ { name: "三级抗震螺纹钢", type: "热轧带肋钢筋（盘卷）", material: "HRB400E", specification: "Φ10", }, { name: "三级抗震螺纹钢", type: "热轧带肋钢筋（盘卷）", material: "HRB400E", specification: "Φ12", }, ] ];

即将一个一维数组转为二维数组

不难发现，部分数组元素字段存在相同的值，我们以type来将这个数组变为二维数组

/*本该这样写，但是会发现报错，type未找到。原因就是oldArr[i+1]已经超出了oldArr，所以会报错*/ let newArr = [],tempArr = []; for(let i=0;i<oldArr.length;i++){ if(oldArr[i].type === oldArr[i+1].type){ tempArr.push(oldArr[i]); }else { tempArr.push(oldArr[i]); newArr.push(tempArr.slice(0)); tempArr.length = 0; } } console.log(newArr) /*所以，我们可以将原来的数组长度+1，即oldArr.push({}),不用填任何数据，就增加一条空数据保证数组长度。接下来就可以这样写*/ let newArr = [],tempArr = []; oldArr.push({}); for(let i=0;i<oldArr.length-1;i++){ if(oldArr[i].type === oldArr[i+1].type){ tempArr.push(oldArr[i]); }else { tempArr.push(oldArr[i]); newArr.push(tempArr.slice(0)); tempArr.length = 0; } } console.log(newArr)

打印的结果就是newArr。

 

那么，又怎么将这个二维数组变回原来数组的格式呢，很简单的

let myArr = []; myArr = [].concat.apply([],newArr); console.log(myArr)

打印结果就是原有数组oldArr的格式

各位小伙伴去试试吧，亲测有效