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JavaScript: Create a new string adding "Py" in front of a given string

JavaScript Basic: Exercise-21 with Solution

Write a JavaScript program to create a new string adding "Py" in front of a given string. If the given string begins with "Py" then return the original string.

Pictorial Presentation:

JavaScript: Create a new string adding

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JavaScript program to create a new string adding “Py” in front of a given string.  If the given string begins with “Py” then return the original string.</title>
</head>
<body>

</body>
</html>

JavaScript Code:

function string_check(str1) {
  if (str1 === null || str1 === undefined || str1.substring(0, 2) === 'Py') 
  {
    return str1;
  }
  return "Py"+str1;
}

console.log(string_check("Python"));
console.log(string_check("thon"));

Sample Output:

Python
Python

Flowchart:

Flowchart: JavaScript - Create a new string adding

ES6 Version:

function string_check(str1) {
  if (str1 === null || str1 === undefined || str1.substring(0, 2) === 'Py') 
  {
    return str1;
  }
  return `Py${str1}`;
}

console.log(string_check("Python"));
console.log(string_check("thon"));

Live Demo:

See the Pen JavaScript: Create new string: basic-ex-21 by w3resource (@w3resource) on CodePen.


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Previous: Write a JavaScript program to check from two given integers, if one is positive and one is negative.
Next: Write a JavaScript program to remove a character at the specified position of a given string and return the new string.

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JavaScript: Tips of the Day

Parameter's value

function getItems(fruitList, ...args, favoriteFruit) {
  return [...fruitList, ...args, favoriteFruit]
}

getItems(["banana", "apple"], "pear", "orange")

...args is a rest parameter. The rest parameter's value is an array containing all remaining arguments, and can only be the last parameter! In this example, the rest parameter was the second parameter. This is not possible, and will throw a syntax error.

function getItems(fruitList, favoriteFruit, ...args) {
  return [...fruitList, ...args, favoriteFruit];
}


getItems(['banana', 'apple'], 'pear', 'orange');
The above example works. This returns the array [ 'banana', 'apple', 'orange', 'pear' ].

Ref: https://bit.ly/3jFRBje