cli

Build a command-line user interface with ease.

Installation

npm install @dnpr/cli

Usage

const { FlagTypes, parseArgv, parseFlagVal } = require("@dnpr/cli")
const { args, flags } = parseArgv(process.argv)
const boolean = parseFlagVal(flags, "-b", FlagTypes.boolean, true)
const number = parseFlagVal(flags, "-n", FlagTypes.number, 100)
const string = parseFlagVal(flags, "-s", FlagTypes.string, "hello")
const obj = parseFlagVal(flags, "-j", FlagTypes.json, { name: "dragonman225" })

API

This library interprets arguments with the following rules:

• An argument starting with "-" is a flag. It is a key-value pair in the form "-key=value". Note that when specifying a value, "=" cannot be omitted.
• An argument not starting with "-" is a normal argument. This library does not process it.

---

parseArgv(argv)

Parse an argument vector into flags and normal arguments.

argv

Type: string[]

@returns

{
  flags: string[], // flags
  args: string[]   // normal arguments
}

---

parseFlagVal(flags, findPrefix, valType, defaultVal)

Parse a flag and return the parsed value in the specified type or return the default value.

flags

Type: string[]

findPrefix

Type: string

e.g. "-flag"

It can also be a regex, such as "(-f|--flag)".

valType

Type: string, must be one of "boolean", "number", "string", "json".

It is recommended to use the FlagTypes constant as shown in Usage instead of directly specifying the strings.

Behavior of each valType:

FlagTypes.boolean — If the flag is found and it has a value, i.e. the "xxx" in "-bool=xxx", this function returns true only when the value is "true". If the flag is found but it has no value, this function returns true. Otherwise, this function returns defaultVal.

FlagTypes.number — If the flag has value, the value is parsed with Number(), if the parsed value is Number.NaN, this function returns defaultVal, otherwise it returns the parsed number. If the flag has no value or it is not found, this function always returns defaultVal.

FlagTypes.string — If the flag has value, this function returns the value. Otherwise, it returns defaultVal.

FlagTypes.json — If the flag has value and the value can be parsed by JSON.parse(), this function returns the value. Otherwise, it returns defaultVal.

defaultVal

Type: any

The type of defaultVal is not checked. The user must ensure that its type is consistent with the specified valType.