Category: JavaScript

To mock object for document element with Jasmine and JavaScript, we use the createSpy method.

For instance, we write

const dummyElement = document.createElement("div");
document.getElementById = jasmine
  .createSpy("HTML Element")
  .and.returnValue(dummyElement);

to call createSpy to create a spy and make it return a value with returnValue.

And we set that as the value of document.getElementById.

Conclusion

To mock object for document element with Jasmine and JavaScript, we use the createSpy method.

Sometimes, we want to add JavaScript object to a JavaScript object

In this article, we’ll look at how to add JavaScript object to a JavaScript object.

How to add JavaScript object to a JavaScript object?

To add JavaScript object to a JavaScript object, we can use an array.

For instance, we write

const jsonIssues = [];
jsonIssues.push({ id: 1, name: "whatever" });

to define the jsonIssues array.

Then we call jsonIssues.push with an object toi append the object into the array.

Conclusion

To add JavaScript object to a JavaScript object, we can use an array.

To retrieve a property of a JSON object by index with JavaScript, we use the Object.values method.

For instance, we write

const obj = {
  set1: [1, 2, 3],
  set2: [4, 5, 6, 7, 8],
  set3: [9, 10, 11, 12],
};

const values = Object.values(obj);
console.log(values[1]);

to call Object.values with obj to return an array of obj property values.

Then we get the 2nd entry from values with values[1].

Conclusion

To retrieve a property of a JSON object by index with JavaScript, we use the Object.values method.

Sometimes, we want to get session id of socket.io client in Client with JavaScript.

In this article, we’ll look at how to get session id of socket.io client in Client with JavaScript.

How to get session id of socket.io client in Client with JavaScript?

To get session id of socket.io client in Client with JavaScript, we use the id property.

For instance, we write

const sio = require("socket.io");
const app = require("express").createServer();

app.listen(8080);
const io = sio.listen(app);

io.on("connection", (client) => {
  console.log("client connected");

  client.send(client.id);

  client.on("disconnect", () => {
    console.log("client disconnected");
  });
});

to call io.on to listen for the connection event.

In the event listener, we get the client’s ID with client.id.

Conclusion

To get session id of socket.io client in Client with JavaScript, we use the id property.

To get img element src and set as variable with JavaScript, we get the src property.

For instance, we write

const imgSrc = document.getElementById("some-img").src;

to select the img element with getElementById.

And then we get its src attribute value with the src property.

If src attribute has a relative path, then the src property would be the resolved path.

Conclusion

To get img element src and set as variable with JavaScript, we get the src property.