Author: John Au-Yeung

Sometimes, we want to create JSON with JavaScript for loop.

In this article, we’ll look at how to create JSON with JavaScript for loop.

How to create JSON with JavaScript for loop?

To create JSON with JavaScript for loop, we can use a for-of loop.

For instance, we write

const sels = [
  //...
];
const json = {};

for (const sel of sels) {
  json[sel.id] = sel.value;
}

to loop through the object entries in the sels array with a for-of loop.

In it, we get the entry being looped through with sel.

We add the sel.id property into json and then assign sel.value to it.

sel.id returned string value would be the property name.

Conclusion

To create JSON with JavaScript for loop, we can use a for-of loop.

Sometimes, we want to turn off antialiasing on an HTML canvas element with JavaScript.

In this article, we’ll look at how to turn off antialiasing on an HTML canvas element with JavaScript.

How to turn off antialiasing on an HTML canvas element with JavaScript?

To turn off antialiasing on an HTML canvas element with JavaScript, we can set context.imageSmoothingEnabled to false to turn off antialiasing for images.

For instance, we write

context.imageSmoothingEnabled = false;

to set the canvas’ context‘s imageSmoothingEnabled property to false to disable antialiasing on images in the canvas.

Conclusion

To turn off antialiasing on an HTML canvas element with JavaScript, we can set context.imageSmoothingEnabled to false to turn off antialiasing for images.

Sometimes,. we want to round to a number of decimal places, but strip extra zeros with JavaScript.

In this article, we’ll look at how to round to a number of decimal places, but strip extra zeros with JavaScript.

How to round to a number of decimal places, but strip extra zeros with JavaScript?

To round to a number of decimal places, but strip extra zeros with JavaScript, we use the number toFixed method and the parseFloat function.

For instance, we write

const n = parseFloat((1.005).toFixed(15));

to call (1.005).toFixed(15) to round 1.005 to 15 decimal places.

Then we pass the returned number string into parseFloat to return the rounded number without the extra trailing zeroes.

Conclusion

To round to a number of decimal places, but strip extra zeros with JavaScript, we use the number toFixed method and the parseFloat function.

Sometimes, we want to pass object by value with JavaScript.

In this article, we’ll look at how to pass object by value with JavaScript.

How to pass object by value with JavaScript?

To pass object by value with JavaScript, we make a copy of the object.

For instance, we write

const obj2 = { ...obj1 };
foo(obj2);

to make a shallow copy of obj1 with the spread operator and assign the copied object to obj2.

Then we call foo with obj2 without affecting obj1.

Conclusion

To pass object by value with JavaScript, we make a copy of the object.

Sometimes, we want to initialize an array with a single value with JavaScript.

In this article, we’ll look at how to initialize an array with a single value with JavaScript.

How to initialize an array with a single value with JavaScript?

To initialize an array with a single value with JavaScript, we can create an empty array and then call map to map each entry to the value we want.

For instance, we write

const arr = [...new Array(1000000)].map(() => 42);

to create array arr with length 1000000.

And then we call map with a callback that maps each entry to 42.

Then arr has 1000000 42’s in it.

Conclusion

To initialize an array with a single value with JavaScript, we can create an empty array and then call map to map each entry to the value we want.