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The if...else if... statement is an advanced form of if…else that allows JavaScript to make a correct decision out of several conditions.SyntaxThe syntax of an if-else-if statement is as follows −if (expression 1){ Statement(s) to be executed if expression 1 is true } else if (expression2){ Statement(s) to be executed if expression 2 is true } else if (expression3){ Statement(s) to be executed if expression 3 is true } else{ Statement(s) to be executed if no expression is true }ExampleYou can try to run the following to learn how to work with if…else if statement in ... Read More
Reserved words cannot be used as JavaScript variables, functions, methods, loop labels, or any object names.Here are the reserved words in JavaScript −abstractElseinstanceofswitchbooleanEnumintsynchronizedbreakExportinterfacethisbyteExtendslongthrowcaseFalsenativethrowscatchFinalnewtransientcharFinallynulltrueclassFloatpackagetryconstForprivatetypeofcontinueFunctionprotectedvardebuggerGotopublicvoiddefaultIfreturnvolatiledeleteimplementsshortwhileDoImportstaticwithdoubleInsuper
The if statement is the fundamental control statement that allows JavaScript to make decisions and execute statements conditionally. SyntaxThe syntax for a basic if statement is as follows −if(expression){ Statement(s)to be executed if expression is true }Here a JavaScript expression is evaluated. If the resulting value is true, the given statement(s) are executed. If the expression is false, then no statement would be not executed. Most of the times, you will use comparison operators while making decisions.ExampleYou can try to run the following to learn how to work with if statement in JavaScript −Live Demo ... Read More
The HTML DOM Parameter Object represent the element of an HTML document.Create param objectSyntaxFollowing is the syntax −document.createElement(“PARAM”);Properties of param objectPropertyExplanationnameIt returns and modify the value of the name attribute of a param element in an HTML document.valueIt returns and modify the content of the value attribute of a param element in an HTML document.ExampleLet us see an example of param object − Live Demo html{ height:100%; } body{ text-align:center; color:#fff; background: linear-gradient(62deg, #FBAB7E 0%, #F7CE68 100%) center/cover no-repeat; ... Read More
The HTML DOM Input Date step property determines the legal day intervals to choose from when user opens the calendar. It sets or returns the input date step attribute value.SyntaxFollowing is the syntax −Returning number valueinputDateObject.stepSetting value attribute to a number valueinputDateObject.step = numberExampleLet us see an example of Input Date step property − Live Demo Input Date required Odd Days Calendar: var divDisplay = document.getElementById("divDisplay"); var inputDate = document.getElementById("dateSelect"); divDisplay.textContent = 'Current step: '+inputDate.step; OutputThis will produce the following output. Here, step was set to 2 −
While naming your variables in JavaScript, keep some rules in mind. The following are the variable naming conventions in JavaScript −You should not use any of the JavaScript reserved keywords as a variable name. These keywords are mentioned in the next section. For example, break or boolean variable names are not valid.JavaScript variable names should not start with a numeral (0-9). They must begin with a letter or an underscore character. For example, 123test is an invalid variable name but _123test is a valid one.JavaScript variable names are case-sensitive. For example, Name and name are two different variables.Here are the Examples −var name; // correct var 2name; ... Read More
The new keyword in JavaScript is the new operator. It creates an instance of a user-defined object type.SyntaxHere’s the syntax −new constructor[([arguments])]ExampleLet us see an example to learn about the usage of new operator − var dept = newObject(); dept.employee = "David"; dept.department = "Programming"; dept.technology = "C++"; document.getElementById("test").innerHTML = dept.employee + "is working on " + dept.technology + " technology.";
Variables can be thought of as named containers. You can place data into these containers and then refer to the data simply by naming the container.While naming your variables in JavaScript, keep the following rules in mind.You should not use any of the JavaScript reserved keywords as a variable name. These keywords are mentioned in the next section. For example, break or boolean variable names are not valid.JavaScript variable names should not start with a numeral (0-9). They must begin with a letter or an underscore character. For example, 123test is an invalid variable name but _123test is a valid one.JavaScript variable names are ... Read More
It performs OR operation on the right operand with the left operand and assigns the result to the left operand.ExampleYou can try to run the following code to learn how to work with Bitwise OR Assignment Operator − var a = 2; // Bit presentation 10 var b = 3; // Bit presentation 11 document.write("(a |= b) => "); document.write(a |= b);
Yes, this can be done. When you have a global scope, you can use a variable without declaring it. The following “no var” variable “points” will look at the scope chain, wince var keyword isn’t use − var rank = 5; points = 50; marks = 300; // Anonymous function (function() { points = 100; //overwrites global scope points var rank = 4; //new rank variable is created in this' function's scope var marks = 900; document.write(rank+"\r"); //prints 4 document.write(points+"\r"); //prints 100 document.write(marks+"\r"); //prints 900 })(); document.write(''); document.write(''); document.write(rank+"\r"); //prints 5 document.write(points+"\r"); //prints 100 document.write(marks+"\r"); //prints 300