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- 'use strict';
- var GetIntrinsic = require('get-intrinsic');
- var $Number = GetIntrinsic('%Number%');
- var $TypeError = GetIntrinsic('%TypeError%');
- var $isNaN = require('../helpers/isNaN');
- var IsStringPrefix = require('./IsStringPrefix');
- var StringToBigInt = require('./StringToBigInt');
- var ToNumeric = require('./ToNumeric');
- var ToPrimitive = require('./ToPrimitive');
- var Type = require('./Type');
- var BigIntLessThan = require('./BigInt/lessThan');
- var NumberLessThan = require('./Number/lessThan');
- // https://262.ecma-international.org/13.0/#sec-islessthan
- // eslint-disable-next-line max-statements, max-lines-per-function
- module.exports = function IsLessThan(x, y, LeftFirst) {
- if (Type(LeftFirst) !== 'Boolean') {
- throw new $TypeError('Assertion failed: LeftFirst argument must be a Boolean');
- }
- var px;
- var py;
- if (LeftFirst) {
- px = ToPrimitive(x, $Number);
- py = ToPrimitive(y, $Number);
- } else {
- py = ToPrimitive(y, $Number);
- px = ToPrimitive(x, $Number);
- }
- var pxType = Type(px);
- var pyType = Type(py);
- if (pxType === 'String' && pyType === 'String') {
- if (IsStringPrefix(py, px)) {
- return false;
- }
- if (IsStringPrefix(px, py)) {
- return true;
- }
- /*
- c. Let k be the smallest non-negative integer such that the code unit at index k within px is different from the code unit at index k within py. (There must be such a k, for neither String is a prefix of the other.)
- d. Let m be the integer that is the numeric value of the code unit at index k within px.
- e. Let n be the integer that is the numeric value of the code unit at index k within py.
- f. If m < n, return true. Otherwise, return false.
- */
- return px < py; // both strings, neither a prefix of the other. shortcut for steps 3 c-f
- }
- var nx;
- var ny;
- if (pxType === 'BigInt' && pyType === 'String') {
- ny = StringToBigInt(py);
- if ($isNaN(ny)) {
- return void undefined;
- }
- return BigIntLessThan(px, ny);
- }
- if (pxType === 'String' && pyType === 'BigInt') {
- nx = StringToBigInt(px);
- if ($isNaN(nx)) {
- return void undefined;
- }
- return BigIntLessThan(nx, py);
- }
- nx = ToNumeric(px);
- ny = ToNumeric(py);
- var nxType = Type(nx);
- if (nxType === Type(ny)) {
- return nxType === 'Number' ? NumberLessThan(nx, ny) : BigIntLessThan(nx, ny);
- }
- if ($isNaN(nx) || $isNaN(ny)) {
- return void undefined;
- }
- if (nx === -Infinity || ny === Infinity) {
- return true;
- }
- if (nx === Infinity || ny === -Infinity) {
- return false;
- }
- return nx < ny; // by now, these are both nonzero, finite, and not equal
- };
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