To fix Node.js: SyntaxError: Cannot use import statement outside a module with JavaScript, we can create and import CommonJS modules.
For instance, we write
mod.js
module.exports.func = () => {
console.log("Hello World");
};
We export the func function in the mod.js module file.
Then we write
const myMod = require("./mod");
myMod.func();
to call require to import mod.js.
And then we call myMod.func, which should log 'Hello World'.
Sometimes, we want to limit panning in Google maps API V3 and JavaScript.
In this article, we’ll look at how to limit panning in Google maps API V3 and JavaScript.
To limit panning in Google maps API V3 and JavaScript, we can create a bounds object and check against it.
For instance, we write
const allowedBounds = new google.maps.LatLngBounds(
new google.maps.LatLng(70.33956792419954, 178.01171875),
new google.maps.LatLng(83.86483689701898, -88.033203125)
);
const lastValidCenter = map.getCenter();
google.maps.event.addListener(map, "center_changed", () => {
if (allowedBounds.contains(map.getCenter())) {
lastValidCenter = map.getCenter();
return;
}
map.panTo(lastValidCenter);
});
to call addListener to listen to the center_changed event.
Then event handler is run when we pan the map.
In the event handler, we check if the center is in the bounds with allowedBounds.contains(map.getCenter()).
If it is, we pan with panTo.
Otherwise, we move back to lastValidCenter.
We create the allowedBounds object with the LatLngBounds constructor called with 2 LatLng objects.
To limit panning in Google maps API V3 and JavaScript, we can create a bounds object and check against it.
Sometimes, we want to resize a Base64 image in JavaScript without using canvas.
In this article, we’ll look at how to resize a Base64 image in JavaScript without using canvas.
To resize a Base64 image in JavaScript without using canvas, we can create an off-screen canvas component.
For instance, we write
const imageToDataUri = (img, width, height) => {
const canvas = document.createElement("canvas"),
ctx = canvas.getContext("2d");
canvas.width = width;
canvas.height = height;
ctx.drawImage(img, 0, 0, width, height);
return canvas.toDataURL();
};
to define the imageToDataUri function.
In it, we create a canvas with createElement.
Then we get the canvas with canvas.getContext.
Next, we set the width and height of the canvas to the size we want.
Then we call drawImage to draw the image with the width and height.
And finally we call canvas.toDataURL to return the resized image as a base64 string.
To resize a Base64 image in JavaScript without using canvas, we can create an off-screen canvas component.
Sometimes, we want to get the height of an element minus padding, margin, border widths with JavaScript.
In this article, we’ll look at how to get the height of an element minus padding, margin, border widths with JavaScript.
To get the height of an element minus padding, margin, border widths with JavaScript, we get the offsetWidth and offsetHeight and subtract them by the padding and border width and height.
For instance, we write
const cs = getComputedStyle(element);
const paddingX = parseFloat(cs.paddingLeft) + parseFloat(cs.paddingRight);
const paddingY = parseFloat(cs.paddingTop) + parseFloat(cs.paddingBottom);
const borderX =
parseFloat(cs.borderLeftWidth) + parseFloat(cs.borderRightWidth);
const borderY =
parseFloat(cs.borderTopWidth) + parseFloat(cs.borderBottomWidth);
const elementWidth = element.offsetWidth - paddingX - borderX;
const elementHeight = element.offsetHeight - paddingY - borderY;
to call getComputedStyle to get an object with the computed styles of element.
Then we get the horizontal padding with
const paddingX = parseFloat(cs.paddingLeft) + parseFloat(cs.paddingRight);
We get the vertical padding with parseFloat(cs.paddingTop) + parseFloat(cs.paddingBottom).
Horizontal border we get with parseFloat(cs.borderLeftWidth) + parseFloat(cs.borderRightWidth).
Vertical border we get with parseFloat(cs.borderTopWidth) + parseFloat(cs.borderBottomWidth).
Then we get the width and height without the border and padding with
const elementWidth = element.offsetWidth - paddingX - borderX;
const elementHeight = element.offsetHeight - paddingY - borderY;
To get the height of an element minus padding, margin, border widths with JavaScript, we get the offsetWidth and offsetHeight and subtract them by the padding and border width and height.
Sometimes, we want to fix PassportJS in Node not removing session on logout with JavaScript.
In this article, we’ll look at how to fix PassportJS in Node not removing session on logout with JavaScript.
To fix PassportJS in Node not removing session on logout with JavaScript, we can use the req.session.destroy method.
For instance, we write
app.get("/logout", (req, res) => {
req.session.destroy((err) => {
res.redirect("/");
});
});
to call req.session.destroy to destroy the session.
The callback is run when the session is destroyed.
To fix PassportJS in Node not removing session on logout with JavaScript, we can use the req.session.destroy method.