Typescript String - Complete tutorials with examples


Learn String object Data type

Learn Typescript String tutorials

The string contains a group of characters saved under String object variable name. You need to know basic operations on String How it works? In this tutorial, we will walk through the different methods and examples.

Basic syntax Of String Object creation

`  
var variable_name = new string('CloudHadoop')  
`  

there are many ways we can create a string object in typescript

  
var cloudVariableName= new string('CloudHadoop');  
let newStringExample= '123';

a string is a one of datatype in typescript. Don’t confuse with the String object. The difference between string and String is String is a type in javascript and string is of typescript

The empty or Null check of a String in typescript

return true if String is Numeric String also contains numbers in single quotes. To check String is Numeric, first, return the string format then check using isNaN method which checks for the valid number

`  
function checkSuppliedStringisNumeric(strParameter: string | number): boolean  
{  
   return !isNaN(Number(strParameter.toString()));  
}  
console.log(checkSuppliedStringisNumeric('123')) // outputs true  
console.log(checkSuppliedStringisNumeric('123abc')) // outputs false  
console.log(checkSuppliedStringisNumeric('abc')) // outputs false*+++  
`  

How to remove whitespaces in String object?. 

This is the common requirement for deleting whitespaces from String object we can easily do in many ways. the string provides trim() method which removes from first and last characters of a word, another way is using regular express which removes complete spaces

`  
  
  
console.log("cloud hadoop".replace(/\s/g, "")) // outputs cloudhadoop  
console.log("cloud hadoop".trim()) // outputs cloud hadoop  
  
console.log(" cloud hadoop ".replace(/\s/g, "")) // outputs cloudhadoop  
console.log(" cloud hadoop ".trim()) // outputs cloud hadoop  
`  

String for each iteration Example. 

First, we will see how String array is created in typescript. string type can be declared after variable followed by a semicolon iteration of strings can be achieved using forEach or for-in loop functionality

`  
  
var msgs: string[] = ['string1', 'string2', 'string3'];  
var output;  
// _ForEach String array  iteration example_  
msgs.forEach(function(entry) {  
     console.log(entry);  
});  
// _For-In String array iteration example  
_for(const msg in msgs) {  
        console.log(msgs[msg]);  
}  
// _For-Of String array iteration example  
_for (const m of msgs) {  
    console.log(m);  
}  
// _plain For loop String  array iteration example_  
for (let i = 0; i < msgs.length; ++i) {  
    console.log (msgs[i]);  
}  
`  

There are many ways to loop String array. for-in and plain for loop using index mechanism to iterate elements and order not guaranteed. whereas forEach and forOf iterates over each String array object.

typescript Split String into an array of Substrings example

Using substring, we can split a string using spaces

`  
  
var message = "[cloud,hadoop,examples,tutorials]";  
function splitStringIntoArray(input) {  
 var messages = input.substring(1, input.length-1).split(", ");  
 return messages;  
}  
document.body.innerHTML = splitStringIntoArray(message)[0] + " " + splitStringIntoArray(message)[1] + " " + splitmessages(message)[2];  
`  

How to convert String to a Boolean example. 

strings contain true or false values. if we passed string boolean values return as a string, else return undefined. Here undefined means not able to parse to boolean type

`  
  
  
function transferToBoolean(input: string): boolean | undefined {  
    try {  
        return JSON.parse(input);  
    }  
    catch (e) {  
        return undefined;  
    }  
}  
  
console.log(transferToBoolean("true")); // true  
console.log(transferToBoolean("false")); // false  
console.log(transferToBoolean("invalid")); // undefined  
`  

String type methods

Method

Description

concat

Joining the two strings and return one output string

toLowerCase

return the lowercase of output string

toUpperCase

return the uppercase of the output string

toString

returns the string

substring

returns the substring of starting index to end index

charAt

return character at the specified index in a string

slice

return the portion of a string

Please also see other tutorials from Typescript language

Typescript Tutorials and Examples

Install and Hello World Example

Enum Tutorials and Examples

String Tutorials and Examples

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