JavaScript: Extract a specific number of characters from a string

JavaScript String: Exercise-4 with Solution

Extract Characters

Write a JavaScript function to extract a specified number of characters from a string.

Visual Presentation:

Test Data :
console.log(truncate_string("Robin Singh",4));
"Robi"

Sample Solution:

JavaScript Code:

// Define a function named truncate_string that takes two parameters: str1, representing the input string, and length, representing the maximum length of the truncated string
truncate_string = function (str1, length) {
    // Check if str1 is a string and length is a positive number
    if ((str1.constructor === String) && (length>0)) {
        // If both conditions are met, return a substring of str1 starting from index 0 and ending at length - 1
        return str1.slice(0, length);
    }
};
// Call the truncate_string function with the input string "Robin Singh" and length 4, and log the result to the console
console.log(truncate_string("Robin Singh",4));

Output:

Robi

Explanation:

In the exercise above,

• The code first checks if 'str1' is a string (str1.constructor === String) and if 'length' is a positive number ('length > 0').
• If both conditions are met, it returns a substring of 'str1' starting from index 0 and ending at 'length - 1'.
• If any of the conditions are not met, the function returns 'undefined'. Finally, the code calls the "truncate_string()" function with the input string "Robin Singh" and length 4, and logs the result to the console.

Flowchart:

Live Demo:

See the Pen JavaScript Extract a specific number of characters from a string - string-ex-4 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that extracts the first n characters from a given string.
• Write a JavaScript function that retrieves a substring of specified length from any given position in a string.
• Write a JavaScript function that validates the length parameter and returns an empty string if n is negative.
• Write a JavaScript function that extracts characters using slice() and handles edge cases gracefully.

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