js将字符串中所有的大写字母转成下划线小写

function toUnderscoreLowerCase(str: string) {
    return str.replace(/([A-Z])/g, "_$1").toLowerCase()
}

const camelCaseStr = "CamelCaseString"
const snakeCaseStr = toUnderscoreLowerCase(camelCaseStr)
console.log(snakeCaseStr) // _camel_case_string
console.log(snakeCaseStr.slice(1)) // camel_case_string