Category: JavaScript Answers

To select all child elements except the first with JavaScript, we can use jQuery with the not pseudo-selector to select all elements except the first element.

For instance, if we have the following HTML:

<ul>  
  <li>First item</li>  
  <li>Second item</li>  
  <li>Third item</li>  
</ul>

and we want to select the last 2 li elements, then we can write:

$("li:not(:first-child)").addClass("something");

to get all the li’s that isn’t the first child of the ul element with li:not(:first-child) .

Then we can call addClass on all the selected elements to add the 'something' class to it.

We can also use the gt pseudo-selector to do the same thing.

For instance, we can write:

$("li:gt(0)").addClass("something");

gt(0) means we select every li but the first child.

We can also use the not method to do the same selection with:

$("li").not(':first').addClass("something");

not(‘:first’) also excludes the first child.

Conclusion

To select all child elements except the first with JavaScript, we can use jQuery with the not pseudo-selector to select all elements except the first element.

To create a text input dynamically with JavaScript, we can use the document.createElement method to create the input element.

Then we can call appendChild to append the element to a container element.

For instance, we can write:

const input = document.createElement("input");  
input.type = "text";  
input.className = "css-class-name";  
document.body.appendChild(input);

We call document.createElement with 'input' to create an input element.

Then we set input.type to 'text' to set the type attribute of the created input element to 'text' .

Next, we set input.className to the value of the class attribute.

And finally, we call document.body.appendChild with input to append the input element as the last child of the HTML body element.

We can replace document.body with another container element that we want to attach the input element to as its last child.

To calculate x% of a number with JavaScript, we can divide x by 100 then multiply by the number we want to compute the percentage for.

For instance, we can write:

const x = 35.8
const result = (x / 100) * 10000;
console.log(result)

We assign the percentage number to x .

Then we divide that by 100 to get a decimal number with the fraction that we want to multiply the number with.

We multiply that by 10000 to get 35.8% of 10000 and assign that to result .

Therefore, result is 3580.

To style HTML5 canvas text to be bold or italic, we can set the font property of the 2d canvas context with the style of the text.

For instance, we can write the following HTML:

<canvas style='width: 200px; height: 200px'></canvas>

to add the canvas element.

Then we can write the following JavaScript:

const canvas = document.querySelector("canvas");  
const ctx = canvas.getContext("2d");  
ctx.font = "italic bold 20pt Courier";  
ctx.fillText("Hello World", 10, 50);

to get the canvas with document.querySelector .

Then we call getContext with '2d' to get the 2d canvas context.

Next, we set the font property of the returned context object with a string with the text styles.

italic makes it italic. bold makes it bold. 20pt is the text size. Courier is the font family.

Finally, we call fillText with the text that we want to display and the x and y coordinates of the top left corner of the text.

Now we should see ‘Hello World’ displayed with Courier font, bold, and italic as a result.

To pass an unknown number of arguments into a JavaScript function, we can use the rest syntax to make a function accept an infinite number of arguments.

For instance, we can write:

const printNames = (...names) => {  
  for (const n of names) {  
    console.log(n)  
  }  
}  
printNames('may', 'alex', 'jane')

We have the printNames method that takes the names arguments array.

The 3 dots before names indicates that names is an array of arguments.

The 3 dots form the rest syntax.

Since names is an array, we can loop through it with the for-of loop.

We log all the entries of names that we passed into printNames as arguments in the last line.

Therefore, we get:

may  
alex  
jane

from the console log.