JS: Quote String

3 Ways to Quote a String

• `GRAVE ACCENT quote` → best. 〔see Template String〕
• "QUOTATION MARK" → literal newline char not allowed.
• 'APOSTROPHE quote' → basically same as QUOTATION MARK quote.

QUOTATION MARK Quote

Use QUOTATION MARK quote to enclose string.

"my cat"

Use \" to embed a QUOTATION MARK in a QUOTATION MARK quoted string.

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

APOSTROPHE Quote

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

Use \' for APOSTROPHE in a APOSTROPHE quoted string.

// APOSTROPHE 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 APOSTROPHE and QUOTATION MARK Quoted String

There's basically no difference, except that if you need to embed a APOSTROPHE or QUOTATION MARK , you need to escape it.

Literal Newline in QUOTATION MARK or APOSTROPHE Quoted String Not Allowed

Literal newline in QUOTATION MARK or APOSTROPHE 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

Characters Not Allowed in QUOTATION MARK or APOSTROPHE Quoted String Literal

The following are not allowed.

• U+005C REVERSE SOLIDUS (aka backslash)
• U+000D CARRIAGE RETURN (aka line return)
• U+2028 LINE SEPARATOR
• U+2029 PARAGRAPH SEPARATOR
• U+000A LINE FEED. (aka newline, line return)

If you include them without escape, you get syntax error.

"a
b"

SyntaxError: Invalid or unexpected token

to include these characters, use String Escape Sequence, or Template String .

Use Backslash to Continue a Line

let xx = "c\
d";

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

String Escape Sequence

Use \n for newline.

console.log("cat\ndog");
/*
prints
cat
dog
*/

〔see String Escape Sequence〕