Category: JavaScript Answers

Sometimes, we want to get the user agent with JavaScript.

In this article, we’ll look at how to get the user agent with JavaScript.

How to get the user agent with JavaScript?

To get the user agent with JavaScript, we use the navigator.userAgent property.

For instance, we write

<input type="text" id="UserAgent">

to add an input.

Then we write

document.getElementById('UserAgent').value = navigator.userAgent;

to put the user agent value into the input with navigator.userAgent.

Conclusion

To get the user agent with JavaScript, we use the navigator.userAgent property.

Sometimes, we want to search an array for a substring match in JavaScript.

In this article, we’ll look at how to search an array for a substring match in JavaScript.

How to search an array for a substring match in JavaScript?

To search an array for a substring match in JavaScript, we can use the array filter method.

For instance, we write

const items = ["item 1", "thing", "id-3-text", "class"];
const matches = items.filter((s) => s.includes("thi"));

to call filter with a callback that calls the string includes method to return an array that has strings in items that has the 'thi' substring.

Conclusion

To search an array for a substring match in JavaScript, we can use the array filter method.

Sometimes, we want to check object equality in Jasmine and JavaScript.

In this article, we’ll look at how to check object equality in Jasmine and JavaScript.

How to check object equality in Jasmine and JavaScript?

To check object equality in Jasmine and JavaScript, we can use the toEqual method.

For instance, we write

describe("jasmine.objectContaining", () => {
  let foo;

  beforeEach(() => {
    foo = {
      a: 1,
      b: 2,
      bar: "baz",
    };
  });

  it("matches objects with the expect key/value pairs", () => {
    expect(foo).toEqual(
      jasmine.objectContaining({
        bar: "baz",
      })
    );
  });
});

to call toEqual in the it callback.

We call it with the value returned by jasmine.objectContaining which checks if the foo object has the properties we’re looking for.

Conclusion

To check object equality in Jasmine and JavaScript, we can use the toEqual method.

Sometimes, we want to check if a div does not exist with JavaScript.

In this article, we’ll look at how to check if a div does not exist with JavaScript.

How to check if a div does not exist with JavaScript?

To check if a div does not exist with JavaScript, we can check if null is returned when we try to select an element.

For instance, we write

if (!document.getElementById("given-id")) {
  //...
}

to check if getElementById returns null when we try to select an element by its ID.

If it does, then the element with the ID doesn’t exist.

Conclusion

To check if a div does not exist with JavaScript, we can check if null is returned when we try to select an element.

Sometimes, we want to get time zone from user’s browser using moment-timezone and JavaScript.

In this article, we’ll look at how to get time zone from user’s browser using moment-timezone and JavaScript.

How to get time zone from user’s browser using moment-timezone and JavaScript?

To get time zone from user’s browser using moment-timezone and JavaScript, we call the moment.tz.guess method.

For instance, we write

const tz = moment.tz.guess();

to call moment.tz.guess to return the time zone of the device the user’s browser is running on as a string.

Conclusion

To get time zone from user’s browser using moment-timezone and JavaScript, we call the moment.tz.guess method.