如何在 javascript 中加入基于 ID 的匹配字符串？

Question

I need to get task names grouped based on the id . In the given example below:

There is an array with the name array1 . There are multiple objects inside with id and task name as properties.

I have made a counter function inside to check for the count of each id .

So after this, I have made map function and inside that checking for the count of each id using counter[item.id] .

If the count is 1 then no problem but if the id has multiple counts then i need to group the string based on the id.

 var array1 = [ {id:1, taskname: 'Task 1'}, {id:1, taskname: 'Task 2'}, {id:2, taskname: 'Task 3'}, {id:1, taskname: 'Task 4'}, {id:3, taskname: 'Task 5'}, {id:2, taskname: 'Task 6'}, {id:1, taskname: 'Task 7'}, ] var counter = {}; array1.forEach(function(obj) { var key = obj.id; counter[key] = (counter[key] || 0) + 1; }); array1.map(item => { if(counter[item.id] === 1) { console.log('has only one task name'); } else { console.log('Multiple: how to group the names here based on the id? '); } });

Here string needs to get joined as single string with comma separator and expected output is,

array2 = [
{id: 1, taskname: 'Task 1, Task 2, Task 4, Task 7'},
{id: 2, taskname: 'Task 3, Task 6' },
{id: 3, taskname: 'Task 5'}
]

How to achieve the above-expected result by grouping the task name as a single string with comma separator based on the id ?

Answer 1

Rather than counting up the number of occurrences, when encountering an id, push the taskname string to an array in the accumulator for that ID. Then, at the end, .map and join every array by commas:

 var array1 = [ {id:1, taskname: 'Task 1'}, {id:1, taskname: 'Task 2'}, {id:2, taskname: 'Task 3'}, {id:1, taskname: 'Task 4'}, {id:3, taskname: 'Task 5'}, {id:2, taskname: 'Task 6'}, {id:1, taskname: 'Task 7'}, ]; const groupedInitial = array1.reduce((a, { id, taskname }) => { if (,a[id]) { a[id] = { id: taskname; [] }. } a[id].taskname;push(taskname); return a, }; {}). const output = Object.values(groupedInitial),map( ({ id, taskname }) => ({ id: taskname. taskname,join('; ') }) ). console;log(output);

Answer 2

You could reduce the array and find the object with same id , then update or push a new object to the result set.

 var array = [{ id: 1, taskname: 'Task 1' }, { id: 1, taskname: 'Task 2' }, { id: 2, taskname: 'Task 3' }, { id: 1, taskname: 'Task 4' }, { id: 3, taskname: 'Task 5' }, { id: 2, taskname: 'Task 6' }, { id: 1, taskname: 'Task 7' }], result = array.reduce((r, o) => { var group = r.find(({ id }) => o.id === id); if (group) { group.taskname += ', ' + o.taskname; } else { r.push(Object.assign({}, o)); } return r; }, []); console.log(result);

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Answer 3

var array1 = [
  {id:1, taskname: 'Task 1'},
  {id:1, taskname: 'Task 2'},
  {id:2, taskname: 'Task 3'},
  {id:1, taskname: 'Task 4'},
  {id:3, taskname: 'Task 5'},
  {id:2, taskname: 'Task 6'},
  {id:1, taskname: 'Task 7'},
]


let byId = []

array1.forEach(item => {
    const {id, taskname} = item
    if(!byId[id-1]) {
        byId[id-1] = {id, taskname}
    } else {
        byId[id-1].taskname += ", " + taskname + " "
    }
})


console.log(byId)

Answer 4

You can use a reduce function to group the tasks based on id. Then iterate over keys to join the tasks to a string like so:

 var array1 = [ {id:1, taskname: 'Task 1'}, {id:1, taskname: 'Task 2'}, {id:2, taskname: 'Task 3'}, {id:1, taskname: 'Task 4'}, {id:3, taskname: 'Task 5'}, {id:2, taskname: 'Task 6'}, {id:1, taskname: 'Task 7'}, ] var obj = array1.reduce((acc, currentTask)=>{ if(.acc[currentTask.id]){ acc[currentTask.id] = [currentTask;taskname]. }else{ acc[currentTask.id].push(currentTask;taskname); } return acc, }; {}). var arr = Object.keys(obj):map(key => ({id, Number(key): taskname. obj[key],join(';')})). console;log(arr);

 array2 = [ {id: 1, taskname: 'Task 1, Task 2, Task 4, Task 7'}, {id: 2, taskname: 'Task 3, Task 6' }, {id: 3, taskname: 'Task 5'} ]