Author: John Au-Yeung

Sometimes, we want to omit specific properties from an object in JavaScript.

In this article, we’ll look at how to omit specific properties from an object in JavaScript.

How to omit specific properties from an object in JavaScript?

To omit specific properties from an object in JavaScript, we can create a function that returns an object with the properties we want to keep.

For instance, we write

const exampleFilter = ({ keepMe, keepMeToo }) => ({ keepMe, keepMeToo });

console.log(
  exampleFilter({
    keepMe: "keepMe",
    keepMeToo: "keepMeToo",
    omitMe: "omitMe",
    omitMeToo: "omitMeToo",
  })
);

to define the exampleFilter function.

In it, we destructure the properties from the parameter object.

And then we return an object with the properties we destructured included,

Conclusion

To omit specific properties from an object in JavaScript, we can create a function that returns an object with the properties we want to keep.

Sometimes, we want to spawn and kill a process in Node.js and JavaScript.

In this article, we’ll look at how to spawn and kill a process in Node.js and JavaScript.

How to spawn and kill a process in Node.js and JavaScript?

To spawn and kill a process in Node.js and JavaScript, we can use the spawn and kill functions.

For instance, we write

const kill = require("tree-kill");
const { spawn } = require("child_process");

const scriptArgs = ["myScript.sh", "arg1", "arg2", "youGetThePoint"];
const child = spawn("sh", scriptArgs);

//...
kill(child.pid);

to call spawn to run the sh command with the command arguments in scriptArgs.

Then we call kill with “child.pid` to kill the process with the given PID.

Conclusion

To spawn and kill a process in Node.js and JavaScript, we can use the spawn and kill functions.

Sometimes, we want to prevent typing non-numeric characters in input type number with JavaScript.

In this article, we’ll look at how to prevent typing non-numeric characters in input type number with JavaScript.

How to prevent typing non-numeric characters in input type number with JavaScript?

To prevent typing non-numeric characters in input type number with JavaScript, we can listen for keypress events.

For instance, we write

document.querySelector("input").addEventListener("keypress", (evt) => {
  if (evt.which < 48 || evt.which > 57) {
    evt.preventDefault();
  }
});

to select the input with querySelector.

Then we call addEventListener to listen to the keypress event.

In the event handler, we check if non-numeric keys are pressed with evt.which < 48 || evt.which > 57.

If it’s true, then we call preventDefault to stop the character from being appended into the value.

Conclusion

To prevent typing non-numeric characters in input type number with JavaScript, we can listen for keypress events.

Sometimes, we want to get the DOM element value using pure JavaScript.

In this article, we’ll look at how to get the DOM element value using pure JavaScript.

How to get the DOM element value using pure JavaScript?

To get the DOM element value using pure JavaScript, we use the value property.

For instance, we write

<input id="theId" value="test" />

to add an input.

Then we get the input’s value attribute value with

const value = document.getElementById("theId").value;

We select the input with getElementById.

Then we get its value property to get the input’s value attribute value.

Conclusion

To get the DOM element value using pure JavaScript, we use the value property.

Sometimes, we want to convert JavaScript associative array to JSON.

In this article, we’ll look at how to convert JavaScript associative array to JSON.

How to convert JavaScript associative array to JSON?

To convert JavaScript associative array to JSON, we can use the JSON.stringify method.

For instance, we write

const assocArray = {};
assocArray["a"] = "The letter A";
const json = JSON.stringify(assocArray);

to call JSON.stringify with assocArray to return the stringified version of the assocArray object as a JSON string.

Conclusion

To convert JavaScript associative array to JSON, we can use the JSON.stringify method.