ducha-qianduan/node_modules/rxjs/_esm2015/internal/operators/pluck.js

import { map } from './map';
export function pluck(...properties) {
    const length = properties.length;
    if (length === 0) {
        throw new Error('list of properties cannot be empty.');
    }
    return (source) => map(plucker(properties, length))(source);
}
function plucker(props, length) {
    const mapper = (x) => {
        let currentProp = x;
        for (let i = 0; i < length; i++) {
            const p = currentProp != null ? currentProp[props[i]] : undefined;
            if (p !== void 0) {
                currentProp = p;
            }
            else {
                return undefined;
            }
        }
        return currentProp;
    };
    return mapper;
}
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