Category: JavaScript Answers

To fix getImageData() error The canvas has been tainted by cross-origin data with JavaScript, we set the img element’s crossOrigin attribute.

For instance, we write

img.crossOrigin = "Anonymous";

to let us load cross origin images in an img element with JavaScript without getting cross origin errors.

This works for servers that has the Access-Control-Allow-Origin header set to '*'.

To force page scroll position to top at page refresh in HTML with JavaScript, we add a beforeunload event handler.

For instance, we write

window.onbeforeunload = () => {
  window.scrollTo(0, 0);
};

to set window.onbeforeunload to a function that calls window.scrollTo with 0 and 0.

Then right before the page is refreshed, the function is called to scroll the page to the top.

To put a clear button inside my HTML text input box like the iPhone does, we add a search input.

For instance, we write

<input type="search" placeholder="Search..." />

to add a search input by adding an input element with the type attribute set to search.

To remove padding or margins from Google Charts with JavaScript, we set the width and height of the chart area.

For instance, we write

const options = {
  title: "How Much Pizza I Ate",
  width: 350,
  height: 400,
  chartArea: { width: "100%", height: "80%" },
  legend: { position: "bottom" },
};

to set the chartArea‘s width and height to match the actual width and height to remove any padding or margin from the chart.

To add upload progress indicators for fetch with JavaScript, we use axios.

For instance, we write

const { data } = await axios.request({
  method: "post",
  url: "/example",
  data: myData,
  onUploadProgress: (p) => {
    console.log(p);
  },
});

to call axios.request to make a post request by calling it with an object with method set to 'post'.

We make a request to the '/example' URL.

We set onUploadProgress to a function that logs progress p.