javascript - 将条目附加到嵌套数组中

Question

本质上，我试图得到一个如下所示的数组:

{
    "projects" : [{
        "project" : "Project One",
        "tasks" : [{
            "name" : "Task One"
        }, {
            "name" : "Task Two"
        }, {
            "name" : "Task Three"
        }]
    }, {
        "project" : "Project Two",
        "tasks" : [{
            "name" : "Task One"
        }, {
            "name" : "Task Two"
        }]
    }]
}

我目前有以下数组和一个脚本，它查看任务的每个元素并检查它是否已经在项目名称列表中，如果不在，则插入第一个，应该 如果是，则添加第二个元素，但这就是我有点卡住的地方:

var tasks = [{
        "name" : "Task One",
        "project" : "Project One"
    }, {
        "name" : "Task One",
        "project" : "Project Two"
    }, {
        "name" : "Task Two",
        "project" : "Project One"
    }, {
        "name" : "Task Three",
        "project" : "Project One"
    }, {
        "name" : "Task Two",
        "project" : "Project Two"
    }]


var projectNames = [];
var projects = [];
for ( i = 0; i < tasks.length; i++) {
    if (projectNames.indexOf(tasks[i].project) < 0) {
        // checks to see that it's not the projectNames list, and inserts the first entry
        projectNames.push(tasks[i].project);
        projects.push({
            project : tasks[i].project,
            tasks : {
                name : tasks[i].name
            }
        });
    } else {
        // if that project is already in the list, append the next entry
        var ind = projectNames.indexOf(tasks[i].project);
        projects[ind].tasks.push({
            name : tasks[i].name
        });
    }
}

我的印象是无法使用 projects[ind].tasks.push()，但我不确定用什么来替换它才是正确的？

(同样，如果有任何更好的方法从第一个数组到第二个数组，我总是很乐意学习新东西)

Answer 1

你可以使用 Array#forEach如果已经创建了相同的项目，则对于 thisArg 是一个对象。

var object = { "tasks": [{ "name": "Task One", "project": "Project One" }, { "name": "Task One", "project": "Project Two" }, { "name": "Task Two", "project": "Project One" }, { "name": "Task Three", "project": "Project One" }, { "name": "Task Two", "project": "Project Two" }] },
    result = { projects: [] };

object.tasks.forEach(function (a) {
    if (!this[a.project]) {
        this[a.project] = { project: a.project, task: [] };
        result.projects.push(this[a.project]);
    }
    this[a.project].task.push({ name: a.name });
}, Object.create(null));

console.log(result);