tty-strings
Version:
Tools for working with strings displayed in the terminal
62 lines • 2.2 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
const stripAnsi_1 = require("./stripAnsi");
const graphemeBreak_1 = require("./graphemeBreak");
/**
* Get the length of a string in grapheme clusters. ANSI escape codes will be ignored.
*
* @remarks
* This function is an implementation of UAX #29 grapheme cluster boundary splitting:
* {@link https://www.unicode.org/reports/tr29/tr29-21.html#Grapheme_Cluster_Boundaries}
*
* @example
* ```ts
* import { stringLength } from 'tty-strings';
*
* // '🏳️🌈'.length === 6
* const len = stringLength('🏳️🌈'); // 1
* ```
*
* @param string - Input string to measure.
* @returns The length of the string in graphemes.
*/
function stringLength(string) {
if (typeof string !== 'string')
return 0;
// strip all ansi control chars
const str = (0, stripAnsi_1.default)(string);
// check if input is an empty string after stripping ansi
if (str.length === 0)
return 0;
// initialize character count
let count = 1,
// initialize array to store grapheme break properties
props = [],
// get first code point
cp = str.codePointAt(0),
// get grapheme break property of the first code point
prev = (0, graphemeBreak_1.graphemeBreakProperty)(cp);
// iterate through each code point in the string
for (let i = cp > 0xFFFF ? 2 : 1, n = str.length; i < n; i += 1) {
cp = str.codePointAt(i);
// get grapheme break property of the next code point
const next = (0, graphemeBreak_1.graphemeBreakProperty)(cp);
// check if there is a cluster boundary between the two adjacent code points
if ((0, graphemeBreak_1.shouldBreak)(props, prev, next)) {
// a cluster boundry exists, increment the character count
count += 1;
// reset grapheme break properties array
props = [];
}
else
props.push(prev);
// ignore surrogates
if (cp > 0xFFFF)
i += 1;
prev = next;
}
// return the character count
return count;
}
exports.default = stringLength;
//# sourceMappingURL=stringLength.js.map