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Front End Technology Articles
Page 541 of 652
What happens if we re-declare a variable in JavaScript?
On re-declaring a variable in JavaScript, the variable value still remains the same.ExampleLet’s see an example. Here, we are declaring the variable age −
Read MoreWhat is the difference between Declaring and Initializing a variable in JavaScript?
The following is stated about declaration and initialization of a variable in ECMAScript specification −A var statement declares variables that are scoped to the running execution context’s VariableEnvironment. Var variables are created when their containing Lexical Environment is instantiated and are initialized to undefined when created. [...] A variable defined by a VariableDeclaration with an Initializer is assigned the value of its Initializer’s AssignmentExpression when the VariableDeclaration is executed, not when the variable is created.The above defines the difference:All variables are initialized with the value undefined.Variables declarations are initialized with undefined upon the initialization of their lexical environment.This initialization does ...
Read MoreWhat is Addition Operator (+) in JavaScript?
The addition operator is used to add two operands.ExampleYou can try to run the following code to work with Addition Operator − var a = 33; var b = 10; document.write("a + b = "); result =a + b; document.write(result);
Read MoreWhat is Addition Assignment Operator (+=) in JavaScript?
It adds the right operand to 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 Addition Assignment Operator − var a = 33; var b = 10; document.write("Value of a => (a += b) => "); result = (a += b); document.write(result); document.write(linebreak);
Read MoreHow to declare boolean variables in JavaScript?
A boolean variable in JavaScript has two values True or False.ExampleYou can try to run the following code to learn how to work with Boolean variables − 35 > 20 Click for result function myValue() { document.getElementById("test").innerHTML = Boolean(35 > 20); }
Read MoreHow to declare numbers in JavaScript?
JavaScript is untyped language. This means that a JavaScript variable can hold a value of any data type. To declare variables in JavaScript, you need to use the var keyword. Whether it is a number or string, use the var keyword for declaration.Here’s how you can declare numbers in JavaScript −var points = 100; var rank = 5;ExampleYou can try to run the following code to learn how to declare number in JavaScript −
Read MoreWhat is unsigned Right Shift Operator (>>>) in JavaScript?
This operator is just like the >>operator, except that the bits shifted in on the left are always zero i.e. xeroes are filled in from the left.ExampleYou can try to run the following code to learn how to work with unsigned right shift operator − var a =-14; var b =2; // Shift right two bits document.write("(a >>> b) => "); result =(a >>> b); document.write(result);
Read MoreHow and why to avoid global variables in JavaScript?
Avoid global variables or minimize the usage of global variables in JavaScript. This is because global variables are easily overwritten by other scripts. Global Variables are not bad and not even a security concern, but it shouldn’t overwrite values of another variable.On the usage of more global variables in our code, it may lead to a maintenance issue. Let’s say we added a variable with the same name. In that case, get ready for some serious bugs.To avoid the usage of global variables, use the local variables and wrap your code in closures. You can also avoid this by wrapping ...
Read MoreHow to write inline JavaScript code in HTML page?
Inline JavaScript Code − If you are adding some JavaScript code in an HTML file without using the src tag then it is known as inline JavaScript code. That’s all you need to know.
Read MoreIs it better to have one big JavaScript file or multiple light files?
To avoid multiple server requests, group your JavaScript files into one. Whatever you use for performance, try to minify JavaScript to improve the load time of the web page.If you are using single page application, then group all the scripts in a single file.If you are using multiple files, then minify all of your scripts and separate them into categories.example - Place JavaScript to be used in every page. This can be the core script of the file. - Place your plugins hereRest, add other scripts in a JavaScript file. It’s good to maintain it in different files.
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