Learn how to add borders to images based on their orientation using if else statement in JavaScript. Also, see how to style borders in CSS.
how to add borders to images within an if else statement in script
Here's an example code for adding borders to images within an if else statement in JavaScript:
javascript Copy code
// Get the image element
var image = document.getElementById("myImage");
// Check if the image is landscape or portrait
if (image.width > image.height) {
// If landscape, add a red border
image.style.border = "5px solid red";
} else {
// If portrait, add a blue border
image.style.border = "5px solid blue";
}
You can customize the border style and color according to your preferences. Make sure to replace "myImage" with the ID of your image element in the HTML code.
In CSS, you can also set the border for all images in your HTML using the following code:
css Copy code
img {
border: 5px solid black;
}
This will add a 5px black border to all images within your HTML file. You can also customize the CSS properties such as the border-style, border-width, and border-color.
how to use trim in js
In JavaScript, the trim()
method is used to remove whitespace from both ends of a string. This is useful when you want to clean up user input.
Here's how you can use it:
javascript Copy code
let myString = " Hello, World! ";
let trimmedString = myString.trim();
console.log(trimmedString); // "Hello, World!"
In this example, trim()
removes the spaces before "Hello," and after "World!" and gives us a clean string.
You can find more information about string methods in JavaScript here.
What is const
const
is a keyword in JavaScript that is used to declare a variable whose value cannot be changed (or reassigned) after it is defined. It stands for "constant". This means that once you set a value to a variable using const
, you cannot change that value later in the code.
Here's a simple example:
javascript Copy code
const pi = 3.14;
console.log(pi); // Outputs: 3.14
// This line would cause an error because you cannot reassign a constant variable
// pi = 3.14159; // Uncaught TypeError: Assignment to constant variable.
For more information, you can check the MDN Web Docs on const.
Math functions in js
In JavaScript, you can use built-in math functions to perform various mathematical operations. Here are some common ones:
Math.abs() - Returns the absolute value of a number.
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console.log(Math.abs(-5)); // Output: 5
Math.round() - Rounds a number to the nearest integer.
javascript Copy code
console.log(Math.round(4.7)); // Output: 5
Math.max() - Returns the largest of the numbers given as arguments.
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console.log(Math.max(1, 2, 3, 4)); // Output: 4
Math.min() - Returns the smallest of the numbers given as arguments.
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console.log(Math.min(1, 2, 3, 4)); // Output: 1
Math.sqrt() - Returns the square root of a number.
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console.log(Math.sqrt(16)); // Output: 4
Math.random() - Returns a floating-point, pseudorandom number between 0 (inclusive) and 1 (exclusive).
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console.log(Math.random()); // Output: A random number between 0 and 1
You can check the MDN Web Docs - Math for more information and additional math functions available in JavaScript.
what does setInterval(() mean?
setInterval()
is a function in JavaScript that allows you to repeatedly execute a piece of code at a specified time interval. It takes two arguments: the first is a function to run, and the second is the time in milliseconds between each execution.
Here’s a simple example:
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let count = 0;
const intervalId = setInterval(() => {
count++;
console.log(count); // This will log the number every second
}, 1000); // Executes every 1000 milliseconds (1 second)
In this example, the number will increase by one every second and be logged to the console. To stop the interval, you can use clearInterval(intervalId);
where intervalId
is the identifier returned by setInterval()
.
For more information, you can refer to the MDN web docs on setInterval.
Explain how == and === are different in JavaScript.
In JavaScript, ==
and ===
are both comparison operators, but they work differently:
==
is the equality operator. It checks if two values are equal, but it performs type conversion if the values are of different types. For example:javascript Copy code
console.log(5 == '5'); // true, because '5' is converted to a number
===
is the strict equality operator. It checks if two values are equal and of the same type. No type conversion occurs. For example:javascript Copy code
console.log(5 === '5'); // false, because the types are different (number vs string)
In summary, use ==
when you want to check for equality regardless of type, and use ===
when you want to check for equality and ensure the types match. It is generally recommended to use ===
to avoid unexpected results due to type conversion.
what is Node.js
Node.js is an open-source, cross-platform runtime environment that allows you to run JavaScript code on the server side. This means you can build server applications using JavaScript, which is traditionally a client-side language.
Here's a simple example of a Node.js server:
javascript Copy code
const http = require('http');
const server = http.createServer((req, res) => {
res.statusCode = 200;
res.setHeader('Content-Type', 'text/plain');
res.end('Hello, World!\n');
});
const PORT = 3000;
server.listen(PORT, () => {
console.log(`Server running at http://localhost:${PORT}/`);
});
In this code, we create a basic web server that responds with "Hello, World!" when accessed. You can run this code using Node.js to see it in action. For more information, you can visit the Node.js website.
how to get milliseconds in javascript
To get the current time in milliseconds in JavaScript, you can use the Date.now()
method or the getTime()
method of a Date
object. Both will give you the number of milliseconds since January 1, 1970, 00:00:00 UTC.
Here’s how to do it using both methods:
Using Date.now()
:
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let currentMilliseconds = Date.now();
console.log(currentMilliseconds);
Using new Date()
and getTime()
:
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let currentMilliseconds = new Date().getTime();
console.log(currentMilliseconds);
Both of these will output the current time in milliseconds. You can try running these in your browser's console.
how does return in JS work
In JavaScript, the return
statement is used to stop the execution of a function and send a value back to where the function was called. When a function executes a return
statement, it exits right away, and any code after that return
is not executed.
Here's a simple example:
javascript Copy code
function add(a, b) {
return a + b; // This will return the sum of a and b
}
let result = add(3, 4); // Calling the function with 3 and 4
console.log(result); // This will print 7
In this example, the function add
takes two parameters a
and b
, and it returns their sum. When we call add(3, 4)
, it computes 3 + 4
, returns 7
, and we store that value in result
, which we then print to the console.
You can learn more about functions in MDN Web Docs.
what is the difference between let, var and const
In JavaScript, let
, var
, and const
are used to declare variables, but they have some important differences:
var
: This is the old way of declaring variables. Variables declared with var
are function-scoped, meaning they are only accessible within the function they were declared in. If declared outside a function, they become global. var
can also be re-declared and updated. javascriptCopy codevar x = 10; x = 20; // Allowed var x = 30; // Allowed
let
: This is a newer way to declare variables. Variables declared with let
are block-scoped, meaning they are only accessible within the block {}
they were declared in. They can be updated but not re-declared in the same block. javascriptCopy codelet y = 10; y = 20; // Allowed // let y = 30; // Not allowed in the same block
const
: This is used for constants. Variables declared with const
are also block-scoped and cannot be updated or re-declared. However, if the constant is an object or array, its properties or elements can still be changed. javascriptCopy codeconst z = 10; // z = 20; // Not allowed const arr = [1, 2, 3]; arr.push(4); // Allowed, we can modify the array
In summary:
var
for function-scoped variables.let
for block-scoped variables that can change.const
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