string

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string#

Immutable UTF-16 code-unit sequences. .length counts code units, not Unicode code points; characters outside the BMP take two units. [...s] and Array.from(s) iterate code points.

length on an ASCII string returns the character count.

"hello".length;       // 5

Length on a surrogate-pair character counts the units, not the character.

"🌍".length;          // 2 (surrogate pair)

Iterate code points with the spread.

[..."🌍"].length;     // 1

Common methods.

"hello".toUpperCase();        // "HELLO"

"hello".includes("ell");      // true

"hello".slice(1, 4);          // "ell"

Template literals interpolate with ${expr} and preserve newlines.

const s = "hello";
`${s}, world`;        // "hello, world"

Tagged templates pass the parts and interpolated values into a function. Used by SQL builders, GraphQL, i18n.

function html(strings, ...values) {
  return strings.raw.reduce((acc, s, i) =>
    acc + s + (values[i] != null ? escape(values[i]) : ""), "");
}

References#

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