优化

‘liusuyi’

2023-10-21 ae92b6823499cfab77201b4033922fa373fb37a3

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'use strict';
 
var hasSymbols = require('has-symbols')();
var GetIntrinsic = require('get-intrinsic');
var callBound = require('call-bind/callBound');
var isString = require('is-string');
 
var $iterator = GetIntrinsic('%Symbol.iterator%', true);
var $stringSlice = callBound('String.prototype.slice');
var $String = GetIntrinsic('%String%', true);
 
module.exports = function getIteratorMethod(ES, iterable) {
    var usingIterator;
    if (hasSymbols) {
        usingIterator = ES.GetMethod(iterable, $iterator);
    } else if (ES.IsArray(iterable)) {
        usingIterator = function () {
            var i = -1;
            var arr = this; // eslint-disable-line no-invalid-this
            return {
                next: function () {
                    i += 1;
                    return {
                        done: i >= arr.length,
                        value: arr[i]
                    };
                }
            };
        };
    } else if (isString(iterable)) {
        usingIterator = function () {
            var i = 0;
            return {
                next: function () {
                    var nextIndex = ES.AdvanceStringIndex($String(iterable), i, true);
                    var value = $stringSlice(iterable, i, nextIndex);
                    i = nextIndex;
                    return {
                        done: nextIndex > iterable.length,
                        value: value
                    };
                }
            };
        };
    }
    return usingIterator;
};