Home/JavaScript
  1. Asked: April 23, 2022In:

    How to Print to Console in Javascript

    srikanth tekumudi Junior < Frontend Developer at Phenom /> || Mock Interviewer || Javascript || to teach React || Content Creator

    There are various ways to to console info. Here are some important methods of console API console.log() console.log(123); //number console.log("Hello World!"); //string console.log(10 + 20); //expression console.log(new Date()); //object console.clear() console.log(10); console.log("Hello World!");Read more

    There are various ways to to console info.

    Here are some important methods of console API

    console.log()

    console.log(123); //number 
console.log("Hello World!"); //string 
console.log(10 + 20); //expression 
console.log(new Date()); //object

    console.clear()

    console.log(10); 

console.log("Hello World!"); 

console.clear(); console.log("All above logs cleared");

    console.error()

    let num1 = 10, num2 = 0;
if (num2 !== 0) {
console.log(num1 / num2);
}
else {
console.error("divided by 0");
}

    console.assert()

    console.assert(false, "Statement is false"); 

var num = 10; console.assert(num > 20, "Number is less than 20"); 

console.assert(25 === '25', "25 is not equal to '25'", { "SomeObject": 12345 });

    console.table() :

    const arr = ["a", "b", "c", "d", "e"];
console.table(arr);
const user = {
name: "Henry",
id: "iuA98",
age: 22
}
console.table(user);
o/p: user info in table format

    console.time() and console.timeEnd()

    console.time("trackLoop"); 

for (let i = 0; i < 10000; i++) { } 

console.timeEnd("trackLoop");

0/p: trackerLoop - 1ms

     

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  2. Asked: April 23, 2022In:

    What Does NaN Mean in Javascript

    srikanth tekumudi Junior < Frontend Developer at Phenom /> || Mock Interviewer || Javascript || to teach React || Content Creator
    This answer was edited.

    NaN is Not-A-Number. There are five different types of operations that return NaN:Number cannot be parsed (e.g. parseInt("blabla") or Number(undefined))Math operation where the result is not a real number (e.g. Math.sqrt(-1))Operand of an argument is NaN (e.g. 7 ** NaN)Indeterminate form (e.g. 0 * IRead more

    NaN is Not-A-Number.

    There are five different types of operations that return NaN:
    Number cannot be parsed (e.g. parseInt(“blabla”) or Number(undefined))
    Math operation where the result is not a real number (e.g. Math.sqrt(-1))
    Operand of an argument is NaN (e.g. 7 ** NaN)
    Indeterminate form (e.g. 0 * Infinity, or undefined + undefined)
    Any operation that involves a string and is not an addition operation (e.g. “foo” / 3)

    ex:

    isNaN(NaN); // true

    isNaN(Number.NaN); // true NaN === NaN; // false Number.NaN === NaN; // false

    What is the type of NaN?

    The type of NaN, which stands for Not a Number is, surprisingly, a number. The reason for this is, in computing, NaN is actually technically a numeric data type. However, it is a numeric data type whose value cannot be represented using actual numbers

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  3. Asked: April 23, 2022In:

    How to Convert Set to Array in Javascript

    bragx

    I believe this is onne of the most vital info for me. Annd i'm glad studying your article. However wanna remark on some basic issues, The website taste is wonderful, the articles is truly excellent : D. Just rikght process, cheers

    I believe this is onne of the most vital info for me.
    Annd i’m glad studying your article. However wanna remark on some basic issues, The website taste is
    wonderful, the articles is truly excellent : D. Just rikght process, cheers

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  4. Asked: June 18, 2022In:

    What is innerhtml in javascript

    srikanth tekumudi Junior < Frontend Developer at Phenom /> || Mock Interviewer || Javascript || to teach React || Content Creator
    This answer was edited.

    InnerHTML is a property of every element. It tells you what is between the starting and ending tags of the element, and it also let you sets the content of the element. innerHTML will show the value and apply any HTML formatting. Ex: HTML: <div id='content'> Hi this is awesome </div> js:Read more

    InnerHTML is a property of every element. It tells you what is between the starting and ending tags of the element, and it also let you sets the content of the element.

    innerHTML will show the value and apply any HTML formatting.

    Ex:

    HTML: 

    <div id='content'> Hi this is awesome </div>

    js: 

    let ele= document.getElementById('content') ele.innerHTML='<h1>text changed </h1>'

    ouput:

     text changed

    (in h1 style) innerHTML apply any HTML formatting in string.

    InnerText:

    InnerText wont apply HTML formatting

    ex:

    let ele= document.getElementById('content') 
    ele.innerText='<h1>text changed </h1>' 

output:

<h1>text changed </h1> (html formatting will not apply here. It is interpreted as String only)
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  5. Asked: June 13, 2022In:

    How to empty an array in JavaScript

    srikanth tekumudi Junior < Frontend Developer at Phenom /> || Mock Interviewer || Javascript || to teach React || Content Creator
    This answer was edited.

    There are  4 ways to empty array: method 1 (set length of variable as 0) ex: let arr=[1,2,3,4,5,6] arr.length=0 console.log(arr) output: [] Method 2 (Assign empty array to variable) ex:  let arr=[1,2,3,4,5,6] arr=[]; console.log(arr) output: [] Method 3 (Using splice) let arr=[1,2,3,4,5,6] arr.splicRead more

    There are  4 ways to empty array:

    method 1 (set length of variable as 0)

    ex:

    let arr=[1,2,3,4,5,6] 

arr.length=0 

console.log(arr)
output: []

    Method 2 (Assign empty array to variable)

    ex: 

    let arr=[1,2,3,4,5,6]
arr=[];
console.log(arr)
output:
[]

    Method 3 (Using splice)

    let arr=[1,2,3,4,5,6] 

    arr.splice(0,arr.length) 

    console.log(arr)

    output:

    []

     

    Method 4 (by popping)

    let arr=[1,2,3,4,5,6]
while(arr.length > 0) {
arr.pop();
}

console.log(arr)

 output: []
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  6. Asked: June 18, 2022In:

    How do I convert Javascript object to json

    srikanth tekumudi Junior < Frontend Developer at Phenom /> || Mock Interviewer || Javascript || to teach React || Content Creator
    This answer was edited.

    short answer:  use JSON.stringify() There are 3 ways to use this: JSON.stringify(value, replacer)JSON.stringify(value)JSON.stringify(value, replacer)JSON.stringify(value, replacer, space) Below is demonstration JSON.stringify(value)// convert obj to jsonex:let obj={"name": "srikanth", age:26, phoneNRead more

    short answer: 

    use JSON.stringify()

    There are 3 ways to use this:

    JSON.stringify(value, replacer)

    JSON.stringify(value)
    JSON.stringify(value, replacer)

    JSON.stringify(value, replacer, space)

    Below is demonstration

    JSON.stringify(value)
    // convert obj to json
    ex:
    let obj={"name": "srikanth", age:26, phoneNo:9321234576}
    let jsonObj=JSON.stringify(obj)
    console.log(jsonObj)

    output:
    {“name”:”srikanth”,”age”:26,”phoneNo”:9321234576}

     

    JSON.stringify(value, replacer)
    ( to select keys in object)

    let obj={"name": "srikanth", age:26, phoneNo:9321234576}

    let jsonObj=JSON.stringify(obj,["name","age"])
    console.log(jsonObj)

    output:
    {“name”:”srikanth”,”age”:26}

    JSON.stringify(value, replacer, space)
     (to format output of stringified json)

    let obj={"name": "srikanth", age:26, phoneNo:9321234576}
    let jsonObj=JSON.stringify(obj,null,' ')
    console.log(jsonObj)

    output:
    {
    “name”: “srikanth”,
    “age”: 26,
    “phoneNo”: 9321234576
    }

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  7. Asked: June 10, 2022In:

    How to Hide API key in Javascript

    Rishikesh Kumar Specialist Freelance Content Stretegist | Technical Writer | Solo Traveller

    When you need to hide the API key in JS you have to define the key as "Password" and on the click event of a button if you need to show that password value set "Text" on button click event.  Suppose you visit login page of gmail. When you type your password it shows like "*********" in this format bRead more

    When you need to hide the API key in JS you have to define the key as “Password” and on the click event of a button if you need to show that password value set “Text” on button click event.

     Suppose you visit login page of gmail.

    When you type your password it shows like “*********” in this format but when you click on an eye button it shows your password.

    So what you need to do in this case when you define such area or something please defined the type as Password and when you want to show that particular set the type as Text on a button click event. 

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  8. Asked: April 1, 2017In:

    How to Import or include a JavaScript file inside another JavaScript file?

    isouravghosh Junior isouravghosh

    Earlier javascript was not having any feature to import and export javascript but since the discovery of ECMAScript 6 (or ES6) you can use the export or import statement in a JavaScript file to export or import variables, functions, classes, or any other entity to/from other JS files. Suppose we havRead more

    Earlier javascript was not having any feature to import and export javascript but since the discovery of ECMAScript 6 (or ES6) you can use the export or import statement in a JavaScript file to export or import variables, functions, classes, or any other entity to/from other JS files.

    Suppose we have two files named script.js and app.js and you want to export variables and functions script.js to app.js Then in the “script.js” file you need to write the export statement as shown in the following example:

    Example :
    let message = “Hi How are you doing?”;
    const PI = 3.14;

    function addNumbers(a, b){
    return a + b;
    }

    // Exporting variables and functions
    export { message, PI, addNumbers };

    And in the “app.js” file you need to write the import statement as shown below:

    import { message, PI, addNumbers } from ‘./script.js’;

    console.log(message); // Prints to the console : Hi How are you doing?
    console.log(PI); // Prints to the console : 3.14
    console.log(addNumbers(10, 10)); // Prints to the console : 20

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  9. Asked: January 6, 2018In:

    How do I append an object to an array in JavaScript?

    Googler Explorer

    Use the push() function to append to an array:[code]// initialize array var arr = [ "Adam", "panju", "keri" ];// append new value to the array arr.push("oraask");console.log(arr);[/code]Will print["Adam", "panju", "keri", "oraask"]

    Use the push() function to append to an array:

    [code]// initialize array
    var arr = [
    “Adam”,
    “panju”,
    “keri”
    ];

    // append new value to the array
    arr.push(“oraask”);

    console.log(arr);[/code]

    Will print

    [“Adam”, “panju”, “keri”, “oraask”]

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  10. Asked: March 27, 2017In:

    How to set a checkbox to be “checked” and “uncheck” with JQuery 1.5 & 1.6 ?

    Googler Explorer

    jQuery 1.6+ Use the new .prop() method: [code]$('.myCheckbox').prop('checked', true); $('.myCheckbox').prop('checked', false);[/code] jQuery 1.5.x and below The .prop() method is not available, so you need to use .attr(). [code]$('.myCheckbox').attr('checked', true); $('.myCheckbox').attr('checked',Read more

    jQuery 1.6+

    Use the new .prop() method:

    [code]$(‘.myCheckbox’).prop(‘checked’, true);
    $(‘.myCheckbox’).prop(‘checked’, false);[/code]

    jQuery 1.5.x and below

    The .prop() method is not available, so you need to use .attr().

    [code]$(‘.myCheckbox’).attr(‘checked’, true);
    $(‘.myCheckbox’).attr(‘checked’, false);[/code]

    Note that this is the approach used by jQuery’s unit tests prior to version 1.6 and is preferable to using

    [code]$(‘.myCheckbox’).removeAttr(‘checked’);[/code]

    since the latter will, if the box was initially checked, change the behaviour of a call to .reset() on any form that contains it – a subtle but probably unwelcome behaviour change.

    For more context, some incomplete discussion of the changes to the handling of the checked attribute/property in the transition from 1.5.x to 1.6 can be found in the version 1.6 release notes and the Attributes vs. Properties section of the .prop() documentation.

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