Grade Calculator

Program to calculate grade based on marks

BeginnerTopic: Conditional Programs

JavaScript Grade Calculator Program

This program helps you to learn the fundamental structure and syntax of JavaScript programming.

// Grade system:
// 90-100: A
// 80-89: B
// 70-79: C
// 60-69: D
// Below 60: F

function calculateGrade(marks) {
    if (marks >= 90 && marks <= 100) {
        return 'A';
    } else if (marks >= 80 && marks < 90) {
        return 'B';
    } else if (marks >= 70 && marks < 80) {
        return 'C';
    } else if (marks >= 60 && marks < 70) {
        return 'D';
    } else if (marks >= 0 && marks < 60) {
        return 'F';
    } else {
        return 'Invalid marks';
    }
}

// Test cases
console.log("95 marks:", calculateGrade(95));
console.log("85 marks:", calculateGrade(85));
console.log("75 marks:", calculateGrade(75));
console.log("65 marks:", calculateGrade(65));
console.log("45 marks:", calculateGrade(45));
console.log("105 marks:", calculateGrade(105));

// Method 2: Using switch with ranges
function calculateGrade2(marks) {
    switch(true) {
        case marks >= 90 && marks <= 100:
            return 'A';
        case marks >= 80 && marks < 90:
            return 'B';
        case marks >= 70 && marks < 80:
            return 'C';
        case marks >= 60 && marks < 70:
            return 'D';
        case marks >= 0 && marks < 60:
            return 'F';
        default:
            return 'Invalid marks';
    }
}

console.log("\nUsing switch:");
console.log("92 marks:", calculateGrade2(92));
console.log("78 marks:", calculateGrade2(78));

Output

95 marks: A
85 marks: B
75 marks: C
65 marks: D
45 marks: F
105 marks: Invalid marks

Using switch:
92 marks: A
78 marks: C

Understanding Grade Calculator

This program demonstrates range-based conditional logic.

Grade System

Common grading scale:

A

: 90-100 (Excellent)

B

: 80-89 (Good)

C

: 70-79 (Average)

D

: 60-69 (Below Average)

F

: 0-59 (Fail)

Method 1: If-Else Chain

Checking ranges with AND operator:

if (marks >= 90 && marks <= 100) {
} else if (marks >= 80 && marks < 90) {

    return 'B';
}

// ... and so on

    return 'A';

Range Checking

•marks >= 90 && marks <= 100: Inclusive range

•marks >= 80 && marks < 90: Lower inclusive, upper exclusive

Method 2: Switch with Ranges

Using switch(true) pattern:

switch(true) {
    case marks >= 90 && marks <= 100:
    case marks >= 80 && marks < 90:

        return 'B';
    // ...
}

        return 'A';

Switch(true) Pattern

•Evaluates each case as boolean

•First matching case executes

•Useful for range checks

Input Validation

Always validate input:

if (marks < 0 || marks > 100) {
}

    return 'Invalid marks';

Real-world Applications

•Student grading systems

•Performance evaluation

•Score categorization

•Rating systems

When to Use:

If-else

: Most common, readable

Switch

: Multiple ranges, organized

Let us now understand every line and the components of the above program.

Note: To write and run JavaScript programs, you need to set up the local environment on your computer. Refer to the complete article Setting up JavaScript Development Environment. If you do not want to set up the local environment on your computer, you can also use online IDE to write and run your JavaScript programs.

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