JavaScript: Quote String

Double Quote

Use double straight quote (U+22: QUOTATION MARK) to enclose string.

console.log("my cat");

Use \" for double quote in a double quoted string.

// deno-fmt-ignore
console.log("my \"3\" cat" === `my "3" cat`);

Single Quote

Single Quote (U+27: APOSTROPHE) can also be used.

Use \' for single quote in a single quoted string.

// single quoted string

// deno-fmt-ignore
console.log('my cat');
// my cat

// deno-fmt-ignore
// with escape
console.log('john\'s cat');
// john's cat

Difference Between Double and Single Quoted String

There's basically no difference, except that if you need to include a double/single quote, you need to escape it if it's the same delimiter.

Literal newline in double/single quoted string not allowed

Literal newline in double/single quoted string is not allowed. Use backslash to continue a line.

illegal syntax. Literal newline is not allowed

let xx = "a
b";

error: The module's source code could not be parsed

"a
b"

SyntaxError: Invalid or unexpected token

Use Backslash to Continue a Line

let xx = "c\
d";

console.log(xx === "cd");

String Escape Sequence

Use \n for newline.

let ss = "cat\ndog";

console.log(
  ss === `cat
dog`,
);

[see String Escape Sequence]

Template String

template string is a new in 2015. It lets you have literal newline in string, and variable and expressions in string.

• Template String