TypeScript Strings

Declare a string

A string holds a sequence of characters. Write the type after the name, then a value in double quotes. You do not include a header. tsc already knows string.

const word: string = "TypeScript";
console.log(word);

Concatenate with +

+ joins strings. If one side is a string, the other side is converted to text and glued on. Two number operands still add. Mix a string with a number and you concatenate, so"n=" + 3 is n=3.

const first: string = "Ada";
const last: string = "Lovelace";
const full: string = first + " " + last;
console.log(first);
console.log(full);
console.log(first + " wrote programs");

length and the first character

length is a property, not a call. It is how many characters are in the string. Index[0] is the first character, type string of length 1. Indexes start at zero, so the last character is at length - 1 when the string is not empty.

const word: string = "TypeScript";
console.log(word.length);
console.log(word[0]);
console.log(word[1]);

slice copies a piece

slice(start, end) returns a new string from index start up to, but not including,end. Omit end and it runs to the end. The original string does not change.

const name: string = "StudyGrid";
const tag: string = name.slice(0, 5);
console.log(name);
console.log("first five: " + tag);
console.log(name.slice(5));

Change 5 to 4 and compile again. The slice shortens. C++ usedsubstr for this idea; TypeScript uses slice.

Input is already a string

readLine() at /typescript/try returns a string, including spaces on that line. You do not need a separate “read a word” call. Type a full name in the stdin box, then compile.

Quotes

Double quotes and single quotes both make strings: "A" and 'A' are the same type. TypeScript has no separate char type. Next: math functions on the global Math object.