Q:

Read a JSON list in list

I have a  json like this  :
{
   "Project 
      [id=1, dateDebut=2017-01-13, dateFin=2017-01-18, description=qsd, sponsor=qsd ]"
    :
 [
  {"id":1,"title":"qsd ","description":"qsdqsd","dateFin":"2017-01-26"},
  {"id":2,"title":"sss ","description":"sss","dateFin":"2017-01-26"}
 ]
}

originated from : return new ObjectMapper.write(Map<Project,List<Task>> projectTasks = new LinkedMultiValueMap<>()) ;
EDIT : this is the real response : 
{"Project [id=1, name=qsdsqd, type=null, done=false, dateDebut=2017-01-13, dateFin=2017-01-18, description=qsd, sponsor=qsd, client=qsd, showable=true]":
[{"id":1,"title":"qsd ","description":"qsdqsd","dateFin":"2017-01-26","dateDebut":"2017-01-14","period":null,"done":false,"status":"Actif","priority":"Normal"},
{"id":2,"title":"task 2 ","description":"qsdqsd","dateFin":"2017-01-26","dateDebut":"2017-01-14","period":null,"done":false,"status":"Actif","priority":"Normal"}]}

How can I read the list of tasks in the client side ?

A:

First of all, your JSON is not valid. Are you sure that is a line break between the word Project and [id...]. A valid JSON would be:
{
   "Project [id=1, dateDebut=2017-01-13, dateFin=2017-01-18, description=qsd, sponsor=qsd, ]":
 [
  {"id":1,"title":"qsd ","description":"qsdqsd","dateFin":"2017-01-26"},
  {"id":2,"title":"sss ","description":"sss","dateFin":"2017-01-26"}
 ]
}

You can have object key names like that. But i'ts not very friendly to retrieve data.
If you cannot change your data schema (or just don't want), you can iterate over the Object with the 
Object.keys(obj).forEach ( (key) => {
   console.log('key: ' + key);
   console.log('value: ' + obj[key]);

   /* you can iterate over your value (tasks) here */
   obj[key].forEach( (task) => {
      console.log('task1: ', task);
   });

});  //where obj is your json

Or you can access the first object property with:
obj[Object.keys(obj)[0]]; //where obj is your json

EDIT As pointed by  @André Dion, forEachis best suited to iteration, not map. And we're assuming your response is already parsed from the server (by yourself or by a lib like jquery). If not, you should do a JSON.parse(response); to retrieve the object.

