Category: JavaScript Answers

Sometimes, we want to create an array of integers from 1 to 20 in JavaScript.

In this article, we’ll look at how to create an array of integers from 1 to 20 in JavaScript.

How to create an array of integers from 1 to 20 in JavaScript?

To create an array of integers from 1 to 20 in JavaScript, we can use the JavaScript array instance’s fill and map methods.

For instance, we write:

const arr = Array(20).fill().map((x, i) => i + 1)
console.log(arr)

We can Array with 20 to create an array with 20 empty slots.

Then we call fill to fill the empty slots with undefined.

Finally, we call map with a callback to return the numbers from 1 to 20.

Therefore, arr is [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20].

Conclusion

To create an array of integers from 1 to 20 in JavaScript, we can use the JavaScript array instance’s fill and map methods.

Sometimes, we want to adjust the height of an element to the screen’s height with jQuery.

In this article, we’ll look at how to adjust the height of an element to the screen’s height with jQuery.

How to adjust the height of an element to the screen’s height with jQuery?

To adjust the height of an element to the screen’s height with jQuery, we can call the css method.

For instance, we write:

<div style='background-color: green'>

</div>

to add a div.

Then we write:

const div = $('div');
div.css("height", `${$(window).height()}px`);

We select the div with $.

Then we call div.css with 'height' and the height of window which we get with $(window).height().

We’ve to add the unit at the end to set the height.

Conclusion

To adjust the height of an element to the screen’s height with jQuery, we can call the css method.

Sometimes, we want to use jQuery to check whether at least one checkbox is checked.

In this article, we’ll look at how to use jQuery to check whether at least one checkbox is checked.

How to use jQuery to check whether at least one checkbox is checked?

To use jQuery to check whether at least one checkbox is checked, we can selected the checked checkboxes and get the length of that.

For instance, we write:

<form>
  <input type="checkbox" value="true" checked="true" name="chk[120]">
  <input type="checkbox" value="true" checked="true" name="chk[128]">
  <input type="checkbox" name="chk[130]">
  <input type="checkbox" name="chk[143]">
  <input type="submit" name="btnsubmit" value="Submit">
</form>

to add a form with some checkboxes.

Then we write:

const someChecked = $('form input:checked').length > 0
console.log(someChecked)

We select the checked checkboxes with $('form input:checked').

And we use length to get the number of checked checkboxes selected.

Therefore, someChecked should be true since some checkboxes are checked.

Conclusion

To use jQuery to check whether at least one checkbox is checked, we can selected the checked checkboxes and get the length of that.

Sometimes, we want to get the first element rather than using [0] in jQuery.

In this article, we’ll look at how to get the first element rather than using [0] in jQuery.

How to get the first element rather than using [0] in jQuery?

To get the first element rather than using [0] in jQuery, we can use the get method.

For instance, we write:

<div>
  foo
</div>
<div>
  bar
</div>
<div>
  baz
</div>

to add a few divs.

Then we write:

const el = $('div').get(0) 
console.log(el)

to select all the divs with $.

Then we call get with 0 to return the first one selected.

Therefore, el is the div with text ‘foo’.

Conclusion

To get the first element rather than using [0] in jQuery, we can use the get method.

Sometimes, we want to get the min/max values among properties of object.

In this article, we’ll look at how to get the min/max values among properties of object.

How to get the min/max values among properties of object?

To get the min/max values among properties of object, we can use the Object.values method to return array with the property values of an object.

Then we can use the Math.min and Math.max to get the min and max value from the array of values respectively.

For instance, we write:

const obj = {
  a: 4,
  b: 0.5,
  c: 0.35,
  d: 5
};

const arr = Object.values(obj);
const min = Math.min(...arr);
const max = Math.max(...arr);

console.log(min, max);

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

Then we call Math.min and Math.max with arr spread into them as arguments to compute the min and max values of arr respectively.

Therefore min is 0.35 and max is 5.

Conclusion

To get the min/max values among properties of object, we can use the Object.values method to return array with the property values of an object.

Then we can use the Math.min and Math.max to get the min and max value from the array of values respectively.