Category: JavaScript Answers

Sometimes, we want to open Blob URL on Chrome iOS with JavaScript.

In this article, we’ll look at how to open Blob URL on Chrome iOS with JavaScript.

How to open Blob URL on Chrome iOS with JavaScript?

To open Blob URL on Chrome iOS with JavaScript, we can use the FileReader constructor.

For instance, we write:

const reader = new FileReader();
const out = new Blob(['abc'], {
  type: 'text/plain'
});
reader.onload = (e) => {
  console.log(reader.result)
}
reader.readAsDataURL(out);

We create a new FileReader instance.

Then we create a new Blob instance that we pass into the readAsDataURL method to read the blob into a base64 data URL.

Then in the reader.onload method, we get the data URL from the reader.result property.

Conclusion

To open Blob URL on Chrome iOS with JavaScript, we can use the FileReader constructor.

Sometimes, we want to generate a random number between 2 values to 2 decimals places in JavaScript.

In this article, we’ll look at how to generate a random number between 2 values to 2 decimals places in JavaScript.

How to generate a random number between 2 values to 2 decimals places in JavaScript?

To generate a random number between 2 values to 2 decimals places in JavaScript, we can use the Math.floor and Math.random methods.

For instance, we write:

const precision = 100;
const randomNum = Math.floor(Math.random() * (10 * precision - 1 * precision) + 1 * precision) / (1 * precision);
console.log(randomNum)

to call Math.random to generate a number between 0 and 1.

Then we multiply the returned number by (10 * precision - 1 * precision) and add by 1 * precision to return the number in the range we want multiplied by precision.

Then we divide by (1 * precision) to return the number with the precision and range we want.

Therefore, randomNum should be a random number with 2 decimal places since precision is 100.

Conclusion

To generate a random number between 2 values to 2 decimals places in JavaScript, we can use the Math.floor and Math.random methods.

Sometimes, we want to convert an HTML table to an array in JavaScript.

In this article, we’ll look at how to convert an HTML table to an array in JavaScript.

How to convert an HTML table to an array in JavaScript?

To convert an HTML table to an array in JavaScript, we can use the spread operator and some array methods.

For instance, we add a table with:

<table id="cartGrid">
  <thead>
    <tr>
      <th>Item Description</th>
      <th>Qty</th>
      <th>Unit Price</th>
      <th>Ext Price</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>Old Lamp</td>
      <td>1</td>
      <td>107.00</td>
      <td>107.00</td>
    <tr>
      <td>Blue POst</td>
      <td>2</td>
      <td>7.00</td>
      <td>14.00</td>
  </tbody>
</table>

Then we write:

const table = document.querySelector('table')
const arr = [...table.rows].map(r => [...r.querySelectorAll('td, th')].map(td => td.textContent))
console.log(arr)

to get all the tr elements in a node list with table.rows.

Then we spread them into an array.

Next, we call map with a callback that select all the td’s or th’s, spread them into an array, and then call map on them to get their textContent.

As a result, arr is:

[
  [
    "Item Description",
    "Qty",
    "Unit Price",
    "Ext Price"
  ],
  [
    "Old Lamp",
    "1",
    "107.00",
    "107.00"
  ],
  [
    "Blue POst",
    "2",
    "7.00",
    "14.00"
  ]
]

Conclusion

To convert an HTML table to an array in JavaScript, we can use the spread operator and some array methods.