index.js•1.27 kB
'use strict';
var GetIntrinsic = require('get-intrinsic');
var define = require('define-data-property');
var hasDescriptors = require('has-property-descriptors')();
var gOPD = require('gopd');
var $TypeError = require('es-errors/type');
var $floor = GetIntrinsic('%Math.floor%');
/** @type {import('.')} */
module.exports = function setFunctionLength(fn, length) {
if (typeof fn !== 'function') {
throw new $TypeError('`fn` is not a function');
}
if (typeof length !== 'number' || length < 0 || length > 0xFFFFFFFF || $floor(length) !== length) {
throw new $TypeError('`length` must be a positive 32-bit integer');
}
var loose = arguments.length > 2 && !!arguments[2];
var functionLengthIsConfigurable = true;
var functionLengthIsWritable = true;
if ('length' in fn && gOPD) {
var desc = gOPD(fn, 'length');
if (desc && !desc.configurable) {
functionLengthIsConfigurable = false;
}
if (desc && !desc.writable) {
functionLengthIsWritable = false;
}
}
if (functionLengthIsConfigurable || functionLengthIsWritable || !loose) {
if (hasDescriptors) {
define(/** @type {Parameters<define>[0]} */ (fn), 'length', length, true, true);
} else {
define(/** @type {Parameters<define>[0]} */ (fn), 'length', length);
}
}
return fn;
};