Basic And Variables — Part 1 MCQs with Explanations

All these facilities are available in JavaScript. Additionally, all development environments provide syntax to create and use memory variables, constants, and functions.

A Live Wire database driver also supports a number of non-relational databases.

If the script tag is placed after the body tag, then, it will not be evaluated at all. Also, it is always recommended and effective to use the script snippet in the <head> tag.

To minimize storage requirements, JavaScript is always a better say.

In order to load a page, the browser must parse the contents of all script tags, which adds additional time to the page load) By minimizing the amount of JavaScript needed to render the page, and deferring parsing of unneeded JavaScript until it needs to be executed, you can reduce the initial load time of your page.

JavaScript is a versatile programming language that can be written in various ways depending on the context and requirements. The correct answer is all of the mentioned options. Let's break down each option: Option A, "directly into JS file and included into HTML," refers to writing JavaScript code in a separate JS file with a .js extension and then linking that file to an HTML page using the script tag. This is a common approach to organize and reuse JavaScript code. Option B, "directly on the server page," implies writing JavaScript code within a server-side scripting language like PHP, ASP, or Node.js. In this case, the JavaScript code is processed on the server before sending the response to the client. Option C, "directly into HTML pages," involves writing JavaScript code directly within the script tags in an HTML file. This allows for inline scripting and is suitable for small-scale applications or quick prototyping. Therefore, option D, "all of the mentioned," is the correct answer as JavaScript can be written in JS files, included in HTML, written on the server page, or directly into HTML pages based on the specific requirements of the project.

A ”src” attribute could be used to add any external code into the HTML document.

The variables whose values can be changed are called mutable variable types.

Generally, X or x denotes hexadecimal values. So, any integer literal that begins with 0X or 0x denotes a hexadecimal number.

Floating-point literals may also be represented using exponential notation: a real number followed by the letter e (or E), followed by an optional plus or minus sign, followed by an integer exponent. This notation represents the real number multiplied by 10 to the power of the exponent.

When the result of a numeric operation is larger than the largest representable number (overflow), the result is a special infinity value, which JavaScript prints as Infinity. Similarly, when a negative value becomes larger than the largest representable negative number, the result is negative infinity, printed as -Infinity. The infinite values behave as you would expect: adding, subtracting, multiplying, or dividing them by anything results in an infinite value (possibly with the sign reversed.

Division by zero is not an error in JavaScript: it simply returns infinity or negative infinity. There is one exception, however: zero divided by zero does not have a welldefined value, and the result of this operation is the special not-a-number value, printed as NaN.

f is the JavaScript escape sequence that stands for Form feed (u000C).

The not-equal operator !== compares o to null and evaluates to either true or false.

a==b returns a true if a and b refer to the same objec ,so they are equal, else it returns a false.

A non-string can be converted in two ways without using a new operator. false.toString() and String(false).

A function definition expression is a “function literal” in the same way that an object initializer is an “object literal.” A Function definition expression typically consists of the keyword function followed by a comma-separated list of zero or more identifiers (the parameter names) in parentheses and a block of JavaScript code (the function body) in curly braces.

The simplest expressions, known as primary expressions, are those that stand alone — they do not include any simpler expressions. Primary expressions in JavaScript are constant or literal values, certain laguage keywords, and variable references.

The given pattern is applied on the text given in the parenthesis.

An invocation expression is JavaScript’s syntax for calling (or executing) a function or method) It starts with a function expression that identifies the function to be called.

An object creation expression creates a new object and invokes a function (called a constructor) to initialize the properties of that object. Object creation expressions are like invocation expressions except that they are prefixed with the keyword new.

The operator “in” tests whether a particular property exists.

A ternary operator is a conditional operator that takes three operands. In JavaScript, ?: is the ternary operator. It is used for conditional expressions. The syntax is condition ? expr1 : expr2 . Options + , : , and - are not ternary operators.

lvalue is a historical term that means “an expression that can legally appear on the left side of an assignment expression.” In JavaScript, variables, properties of objects, and elements of arrays are lvalues.

JavaScript is not a full-blown OOP (Object-Oriented Programming) language, such as Java or PHP, but it is an object-based language.

The interpreter checks obj for property b, fails and takes it from outside of with.

A conditional expression in JavaScript is also known as an immediate if or ternary operator . The correct answer is option B. Let's understand the other options: Option A, "Alternate to if-else," is not an accurate description of a conditional expression. While a conditional expression can be used as an alternative to if-else in certain cases, it is not its primary name. Option C, "If-then-else statement," is not the commonly used term for a conditional expression. It is more commonly used to refer to the traditional if-else statement structure. Option D, "None of the mentioned," is incorrect because a conditional expression does have a specific name. Therefore, option B, "Immediate if," is the correct answer as it accurately describes the conditional expression in JavaScript. It is called "immediate" because it allows for a concise way of expressing a condition and immediately returning a value based on that condition.

A for loop is always more efficient because it encapsules two individual statements(initialization and expression) within the braces.

A statement block is a block that combines more than one statements into a single compound statement for ease.

The JavaScript interpreter takes no action when it executes an empty statement. The empty statement is occasionally useful when you want to create a loop that has an empty body.

The var and function are declaration statements—they declare or define variables and functions. These statements define identifiers (variable and function names) that can be used elsewhere in your program and assign values to those identifiers.

When a switch executes, it computes the value of expression and then looks for a case label whose expression evaluates to the same value (where sameness is determined by the === operator).

The do/while loop is less commonly used when compared to the while loop. Here, it prints from the array in the given order.

In a for loop, the initialization, the test, and the update are the three crucial manipulations of a loop variable.

The above code uses a for loop to traverse a linked list data structure and return the last object in the list. This will perfectly work.

Before each iteration, the interpreter evaluates the variable expression and assigns the name of the property (a string value) to it.

If the body of a for/in loop deletes a property that has not yet been enumerated, that property will not be enumerated. If the body of the loop defines new properties on the object, those properties will generally not be enumerated.

When an exception is thrown in a jump statement, the interpreter jumps to the nearest enclosing exception handler, which may be in the same function or up the call stack in an invoking function.

Instead of exiting a loop like the break keyword, the continue keyword moves to the next iteration from the place encountered.

The debugger statement normally does nothing. If, however, a debugger program is available and is running, then an implementation may (but is not required to) perform some kind of debugging action. In practice, this statement acts like a breakpoint: execution of JavaScript code stops and you can use the debugger to print variable’s values.