这个代码块在 javascript 语法中是什么意思？

Question

Template.body.helpers({
    tasks() {
      return Tasks.find({});
    },
});

I just know the basics of javaScript..but I saw this piece of code in meteor tutorial and did not understand what it meant,is task an object or a function?How does this actually give info to the HTML page?

Answer 1

Actually, the Template.body.helpers is a dictionary which acts very similar to an object , so you can set multiple properties in it, like functions. The tasks() itself is a function which is responsible returning data from our database (We know the Tasks are like this const Tasks = new Mongo.Collection('tasks'); so it is connected to the tasks table) , in this particular case our query ( find({}) ) does not include any condition so it will return all the data from the tasks table. The meteor engine will take the rest of it where you can refer to your helpers by {{tasks}} .

So you can create as many helpers as you want to do what you desired just like this:

Template.body.helpers({
    tasks() {
      return Tasks.find({});
    },
    foo() {
      return Session.get("foo");
    }
});

Then you can refer both foo and tasks in your HTML like before with {{foo}} and {{tasks}} .

Answer 2

It is the function, to which you are passing an object as an argument. In this object there is method called "tasks".

---

tasks() {
      return Tasks.find({});
}

is the same as

tasks: function(){
    return Tasks.find({});
)

It is ES6 syntax.

Answer 3

It's ES6+.

Template.body.helpers is receiving a JS Object/JSON which has a function called tasks . And it get all the information from Tasks object (defined anywhere in the same code), with empty query (which'd like all).

Template.body.helpers({
  tasks: function () {
    return Tasks.find({});
  },
});