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JavaScript: Find the longest common starting substring in a set of strings

JavaScript Array: Exercise-28 with Solution

Write a JavaScript function to find the longest common starting substring in a set of strings.

Sample array : console.log(longest_common_starting_substring(['go', 'google']));
Expected result : "go"

Pictorial Presentation:

JavaScript: Find the longest common starting substring in a set of strings

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>Write a JavaScript function to find the longest common starting substring in a set of strings</title>
</head>
<body>

</body>
</html>

JavaScript Code:

function longest_common_starting_substring(arr1){
var arr= arr1.concat().sort(),
a1= arr[0], a2= arr[arr.length-1], L= a1.length, i= 0;
while(i< L && a1.charAt(i)=== a2.charAt(i)) i++;
return a1.substring(0, i);
}

console.log(longest_common_starting_substring(['go', 'google'])); 

console.log(longest_common_starting_substring(['SQLInjection', 'SQLTutorial'])); 

console.log(longest_common_starting_substring(['abcd', '1234']));

Sample Output:

go
SQL

Flowchart:

Flowchart: JavaScript: Find the longest common starting substring in a set of strings

ES6 Version:

function longest_common_starting_substring(arr1){
  const arr= arr1.concat().sort();
  const a1= arr[0];
  const a2= arr[arr.length-1];
  const L= a1.length;
  let i= 0;
  while(i< L && a1.charAt(i)=== a2.charAt(i)) i++;
  return a1.substring(0, i);
}

console.log(longest_common_starting_substring(['go', 'google'])); 

console.log(longest_common_starting_substring(['SQLInjection', 'SQLTutorial'])); 

console.log(longest_common_starting_substring(['abcd', '1234']));

Live Demo:

See the Pen JavaScript - Find the longest common starting substring in a set of strings - array-ex- 28 by w3resource (@w3resource) on CodePen.


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Next: Write a JavaScript function to fill an array with values (numeric, string with one character) on supplied bounds.

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JavaScript: Tips of the Day

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = [];
arr[0] = "Jani";
arr[1] = "Hege";
arr[2] = "Stale";
arr[3] = "Kai Jim";
arr[4] = "Borge";

console.log(arr.join());
arr.splice(2, 0, "Lene");
console.log(arr.join());

Ref: https://bit.ly/2BXbp04