How to check a string begins with some given characters/pattern ?

In this article, we will check a string begins with some given characters/pattern. We can check whether a given string starts with the characters of the specified string or not by various methods in javascript which are described below.

Methods to check if a string begins with some given pattern:

• Using JavaScript loops
• Using substring() and localeCompare() Methods
• Using string startsWith() method
• Using JavaScript indexOf() methodmatch

Method 1: Using JavaScript loops

This is a simple approach in which we will match characters one by one from starting using the loop and if any character doesn’t match then we can say that string doesn’t begin with the character or specified string.

Syntax:

for (let i = 0; i < pattern.length; i++) {
        if(str.charAt(i) != pattern.charAt(i)){
            result = false;
            break;
        }
      }

Example: Below program demonstrates the above approach: 

String = "neveropen"
String should begin with = "Geeks"
String begins with "Geeks"
String = "neveropen"
String should begin with = "Geeks"
String doesn't begins with "Geeks"

Method 2: Using substring() and localeCompare() Methods

In this method, we will use the substring() function to get a substring of the required length of the pattern string and then match the substring with a pattern using the localeCompare() function. 

Syntax:

let substr = string.substring(Startindex, Endindex)
string.localeCompare(substr)

Example: Below program demonstrates the above approach: 

String = "neveropen"
String should begin with = "Geeks"
String begins with "Geeks"
String = "neveropen"
String should begin with = "Geeks"
String doesn't begins with "Geeks"

Method 3: Using string startsWith() method

This is the best solution above all, in this method, we will use the startsWith() method to directly check whether the given string starts with something or not.

Syntax:

str.startsWith( searchString , position )

Example: Below program demonstrates the above approach: 

String = "Burn to shine"
String should begin with = "Burn"
String begins with "Burn"
String = "Happy coding"
String should begin with = "happy"
String doesn't begins with "happy"

Method 4: Using JavaScript indexOf() method

Example: In this example, we will use JavaScript string indexOf method to check if the pattern is present at index zero it returns true else it returns false

String = "Burn to shine"
String should begin with = "Burn"
String begins with "Burn"
String = "Happy coding"
String should begin with = "happy"
String doesn't begins with "happy"