For reaching the back page on button click, use the concept of −window.history.go(-1)Example Live Demo Document To run the above program, save the file name “anyName.html(index.html)” and right click on the file. Select the option “Open with Live Server” in VS Code editor.OutputThis will produce the following output −After clicking the button “Click the button to Goto the Previous Page....”, you will reach the previous page as in the below screenshot −

Following is the code −Examplefunction multiplication(firstValue, secondValue, callback) {    var res = firstValue * secondValue;    var err = isNaN(res) ? 'Something is wrong in input parameter' :    undefined;    callback(res, err); } multiplication(10, 50, function (result, error) {    console.log("The multiplication result="+result);    if (error) {       console.log(error);    } }); multiplication('Sam', 5, function (result, error) {    console.log("The multiplication result="+result);    if (error) {       console.log(error);    } });To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo201.js.OutputThis will produce the following output ... Read More

To check this, use the concept of getter, i.e. the get property. Following is the code −Exampleclass Student{    constructor(studentMarks1, studentMarks2){       this.studentMarks1 = studentMarks1       this.studentMarks2 = studentMarks2       var alteredValue = this;       this.getValues = {          get studentMarks1() {             return alteredValue.studentMarks1          },          get studentMarks2() {             return alteredValue.studentMarks2          }       }    } } var johnSmith = new Student(78, 79) console.log("Before ... Read More

Let’s say following is our string −my name is JOHN SMITHUse sort() along with regular expression /[A-Z]/ to move all capital letters to the beginning of the string/Examplevar moveAllCapitalLettersAtTheBeginning = [...' my name is JOHN SMITH '] .sort((value1, value2) => /[A-Z]/.test(value1) ? /[A-Z]/.test(value2) ? 0 : -1 : 0).join(' '); console.log("After moving the all capital letters at the beginning="); console.log(moveAllCapitalLettersAtTheBeginning);To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo199.js.OutputThis will produce the following output −PS C:\Users\Amit\javascript-code> node demo199.js After moving the all capital letters at the beginning= J O H N ... Read More

Use the return keyword for outsider function call. Following is the code −Examplevar substractMethod = function () {    var firstValue =1000, thirdValue= 200;    var divideMethod = function (){       var secondValue =500;       console.log("The result of       divideMethod()="+(firstValue/secondValue));       return (firstValue-secondValue);    }    return divideMethod; } var result = subtractMethod(); console.log("The result of substractMethod()="+result());To run the above program, you need to use the following command −node fileName.js.Here, my file name is demo198.js.OutputThis will produce the following output −PS C:\Users\Amit\javascript-code> node demo198.js The result of divideMethod()=2 The result of subtractMethod()=500

For this, use the concept of toString(‘utf8’). Following is the code −In the code below, there are detailed explanations about the buffer.Examplevar actualBufferObject = Buffer.from('[John Smith]', 'utf8') console.log("The actual buffer object="); console.log(JSON.stringify(actualBufferObject)) console.log("Get back the original object="); console.log(actualBufferObject.toString('utf8')); var myObjectValue = '[John Smith]'; console.log("The data you are getting from the buffer is equal to ASCII code equivalent...") for (var counter = 0; counter < myObjectValue.length; counter++) {    console.log("The ascii value of " + myObjectValue[counter] + " is ="    + (myObjectValue.charCodeAt(counter))); }To run the above program, you need to use the following command −node fileName.js.Here, my file name is ... Read More

In order to get rid of null values inserted into a table, you need to check the condition while entering the value.The condition to check NULL must be as follows −while( !( yourVariableName1==null || yourVariableName2==null || yourVariableName3==null…...N){    // yourStatement1    .    .    N }The above logic will never allow inserting the null values.Now you can use for loop and insert value into the table without NULL. Following is the code −Example Live Demo Document Demo Of Inserting the value into the table This is demo on the javascript ... Read More

Let’s say the following is our array &mius;var subjectNameAlongWithMarks = [    ["JavaScript", 78],    ["Java", 56],    ["JavaScript", 58],    ["MySQL", 77],    ["MongoDB", 75],    ["Java", 98] ]Above, we have repeated values, which we need to remove by comparing the duplicate values 0th index. Use the concept of Set() from JavaScript for this −Examplevar subjectNameAlongWithMarks = [    ["JavaScript", 78],    ["Java", 56],    ["JavaScript", 58],    ["MySQL", 77],    ["MongoDB", 75],    ["Java", 98] ] var distinctResult = subjectNameAlongWithMarks.filter(function ([value]){    return !this.has(value) && !!this.add(value) }, new Set()) console.log(distinctResult);To run the above program, you need to use ... Read More

For this, use jQuery() with id property. Following is the code −Example Live Demo Document    .changeColor {       color: red    }; Javascript MySQL MongoDB Python    jQuery("#selectDemo").click(function () {       jQuery(this).toggleClass("changeColor");       if (jQuery(this).hasClass("changeColor")) {          jQuery(".isSelected").prop("checked", true);          jQuery(this).val("Want To UnSelect All Values");       } else {   ... Read More

Yes, parent and child classes can have a method with the same name.Exampleclass Parent {    constructor(parentValue) {       this.parentValue = parentValue;    }    //Parent class method name which is same as Child Class method name.    showValues() {       console.log("The parent method is called.....");       console.log("the value is="+this.parentValue);    } } class Child extends Parent {    constructor(parentValue, childValue){       super(parentValue);       this.childValue = childValue;    }    //Child class method name which is same as Parent Class method name.    showValues() {       console.log("The child ... Read More