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The `substr` function is used to extract a portion of a string. It takes two arguments: the starting index and the length of the substring. The starting index is the position of the first character to be included in the substring. The length is the number of characters to be included in the substring.
Here is an example of how to use the `substr` function in TypeScript:
let str: string = "Hello, world!";
let substr: string = str.substr(7, 5);
console.log(substr); // Output: "world"
In this example, the `substr` function is used to extract the word “world” from the string “Hello, world!”. The starting index is 7, which is the position of the letter “w” in the string. The length is 5, which is the number of characters in the word “world”.
In conclusion, the `substr` function in TypeScript is a useful tool for extracting substrings from strings. However, it is recommended to use the `substring` or `slice` functions instead for modern code.
In conclusion, the TypeScript String class provides a powerful and flexible way to manipulate strings in a type-safe manner. One of the most useful methods in this class is the substr() function, which allows developers to extract a substring from a larger string based on a specified starting index and length. By using this function, TypeScript developers can easily manipulate strings in their applications with confidence, knowing that their code is both efficient and safe. Whether you are building a simple web application or a complex enterprise system, the substr() function in TypeScript is an essential tool for any developer working with strings.