lib/string.js
function snakeCase(str, sep = '_') {
    return words(str).reduce(
        (result, word, idx) => result + (idx ? sep : '') + lowerCase(word), ''
    );
}
function snakeCase(str, sep = '_') {
    return words(str).reduce(
        (result, word, idx) => result + (idx ? sep : '') + lowerCase(word), ''
    );
}
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下划线
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