First Character is: H

10th Character is: o

Last Character is: ?

How to find a position of specified string in string - indexOf()

In Javascript, in order to check whether a particular substring exists within a string and to find the position of the substring, there is a method called indexOf(). This method returns the index or position of the first occurrence of the specified substring within the string. It takes a sequenced portion of string and returns an index, or the position of the first character of the portion. If a specified substring does not exist within a string, it returns -1. This method accepts a string value as a parameter and returns a number value.

Syntax

string.indexOf(substring);

Example

var str = "How are you doing today?";

console.log("First time 'H' occurs at position: " + str.indexOf("H"));
console.log("First time 'are' occurs at position: " + str.indexOf("are"));
console.log("'Z' is not there in string : " + str.indexOf("Z"));
console.log("'Doing' is not there in string : " + str.indexOf("Doing"));
console.log("'?' sign occurs at position : " + str.indexOf("?"));

Output

The IndexOf() method starts searching from the beginning of a string and returns an index of the first occurrence of the specified string. Similarly, to check from the end of the string, there is a method called lastIndexOf(). It returns an index of the first character of the specified string that occurs last. Additionally, there is a search() method that is similar to the indexOf() method and accepts a regular expression pattern as input and returns the index of the first match of that expression.

Example

var str = "How are you doing today?";

// lastIndexOf() Method
console.log("Last time 'a' occurs at position: " + str.lastIndexOf("a"));
console.log("Last time 'are' occurs at position: " + str.lastIndexOf("are"));

// search() Method with Regular Expression
console.log("First time 'H' occurs at position : " + str.search(/H/));
console.log("'h' is not there in string : " + str.search(/h/));

Output

How to check whether a given string is included in particular string - includes()

In order to determine whether a specified substring exists in a particular string, there is a method called includes(). This method returns a boolean value. If the specified substring exists, it returns true; otherwise, it returns false. This method accepts a string value as a parameter and returns a boolean value. 

Syntax

string.includes(substring);

Example

var str = "How are you doing today?";

console.log("Whether 'How' is included in string: " + str.includes("How"));
console.log("Whether 'how' is included in string: " + str.includes("how"));
console.log("Whether 'today?' is included in string: " + str.includes("today?"));

Output

How to change a certain string's content - replace()

In Javascript, to replace a particular portion of the string, there is a method called replace(). As the name says, it replaces a particular substring with a given substring. It takes two values as a parameter. The first parameter is the string that we want to replace, and the second is the string that we want to replace it with. It only replaces the first occurrence in a string.

If the substring that we want to replace does not exist within a string, it returns the string as it is. It accepts string values as a parameter and also returns a string.

Syntax

string.replace(substring, updateWith);

Example

var str = "How are you doing today?";

console.log("Updated string: " + str.replace("are you", "am I"));
console.log("Updated string: " + str.replace("o", "O")); // will replace only first occurrence
console.log("Updated string: " + str.replace("?", "!"));

Output

How to extract a part of string - slice()

In Javascript, in order to extract a substring from a string, you can use a method called slice(). It takes two number values as a parameter. The substring that we want to extract is specified by these parameters. The first parameter indicates the starting position, and the second parameter specifies the ending position.

Additionally, the slice() method can accept negative values to start extracting the substring from the end of the string. This method accepts number values as a parameter and returns a string value.

Syntax

string.slice(start, end);

Example

var str = "A Scripting and Programming language that allows you to add behaviour to web pages.";

console.log(str.slice(0, 25) + "...");
console.log(str.slice(25, 50) + "...");
console.log(str.slice(-50, -10) + "...");

Output

Javascirpt provides similar methods to extract a substring from a string: substr() and substring().

The substr() method accepts two number values as an argument. The first parameter indicates the starting position of the substring, and the second parameter indicates the length of the substring from the starting position.

Similarly, the substring() method also accepts two number values as arguments. These parameters indicate the starting and ending positions of the substring, respectively.  This method is identical to slice() but treats negative values as zero.

Example

var str = "A Scripting and Programming language that allows you to add behaviour to web pages.";

// substr() Method
console.log(str.substr(0, 25) + "...");
console.log(str.substr(25, 50) + "...");
console.log(str.substr(-50, 10) + "...");

// substring() Method
console.log(str.substring(0, 25) + "...");
console.log(str.substring(25, 50) + "...");
console.log(str.substring(-50, -10) + "..."); // It considers negative value as zero

Output

How to convert string to an array - split()

In Javascript, in order to convert a string into an array, you can use the split() method. It takes a separator string as input and returns an array containing substrings separated by the specified separator. For example, using a space (" ") as the separator will split the string into an array of words.

Additionally, you can set a limit on the number of substrings generated by the separator. You can specify a limit as an optional parameter after the separator. So, this method accepts a string value as a parameter and returns an array value.

Syntax

string.split(separator, limit(optional));

Example

var str = "How are you doing today?";

console.log(str.split(" "));
console.log(str.split(""));
console.log(str.split("to"));
console.log(str.split(" ", 3)); // 3 is a limit argument

Output

How to join or combine two or more string into one string - concat()

The concat() method in Javascript is used to concatenate or merge two or more strings. It takes one or more string arguments that we want to join together or combine with the original string and returns a new combined string. However, you can also use the '+' operator and template literals (`) to merge strings. This method accepts string values as a parameter and returns a string value.

Syntax

string.concat(str1, str2);

Example

var str = "How ";
var str2 = "are you ";
var str3 = "doing today";

console.log(str.concat(str2));
console.log(str.concat(str2, str3));
console.log(str.concat(str2, str3, "?"));
console.log(`${str}${str2}${str3}?`); // Using template literal (``);

Output

How to determine if a string begins with a specific character or string - startsWith()

In Javascript, in order to check whether a string starts with a particular substring, you can use the startsWith() method. It takes a substring as a parameter and determines whether the main string starts with it. It returns boolean values based on the input. So, this method accepts a string as a parameter and returns a boolean value.

Syntax

string.startsWith(substring);

Example

var str = "How are you doing today?";

console.log("This string starts with 'H': " + str.startsWith("H"));
console.log("This string starts with 'How are': " + str.startsWith("How are"));
console.log("This string starts with 'are you': " + str.startsWith("are you"));

Output

Similar to startsWith(), Javascript also provides a method to determine whether a string ends with a particular substring, called the endsWith() method. It also accepts a string as a parameter and returns a boolean value.

Example

var str = "How are you doing today?";

console.log("This string ends with '?': " + str.endsWith("?"));
console.log("This string ends with 'day?': " + str.endsWith("day?"));
console.log("This string ends with 'today': " + str.endsWith("today"));

Output

How to convert string case - toUpperCase() and toLowerCase()

In Javascript, you can change the case of the string using methods such as toUpperCase() and toLowerCase(). These methods don't require any parameters. As name says, the toUpperCase() method converts entire string into an upper case and the toLowerCase() method converts entire string into a lower case. These methods don't accept any parameters and return a string value.

Syntax

string.toUpperCase();
string.toLowerCase();

Example

var str = "How are you doing today?";

// toUpperCase() Method
console.log(str.toUpperCase());

// toLowerCase() Method
console.log(str.toLowerCase());

Output

How to remove whitespace from both side of String - trim()

In Javascript, in order to remove the extra whitespace from both ends of a string, you can use the trim() method. It does not remove whitespace within the string; it only removes space from both ends of the string. This method doesn't require any parameters and returns a trimmed string.

Syntax

string.trim();

Example

var str = "   How are you doing today?   "; // contains whitespace
var str2 = "How are you doing today?"; // does not contain whitespace

console.log(str.trim());
console.log("Both the string are equal: " + (str === str2));
console.log("Both the string are equal: " + (str.trim() === str2));

Output

Conclusion

So far, we've looked at the JavaScript string methods that are used the most. Along with these methods, we also compared related and similar methods. Keep practicing these methods, and you'll gain expertise with JavaScript string manipulation. If you really enjoyed reading this article, share your thoughts in the comment section.