propChecker.js

export function throwIfInvalidProps(props) {
  checks.forEach(check => check.validate(props))
}

class PropCheck {
  constructor(isInvalid, errorText) {
    this.isInvalid = isInvalid
    this.errorText = errorText
  }
  validate = props => {
    if (this.isInvalid(props)) {
      throw new Error(
        `${this.errorText} Check usage of react-native-date-picker.`
      )
    }
  }
}

const widthCheck = new PropCheck(
  props =>
    props &&
    props.style &&
    props.style.width &&
    typeof props.style.width !== 'number',
  'Invalid style: width. Width needs to be a number. Percentages or other values are not supported.'
)

const heightCheck = new PropCheck(
  props =>
    props &&
    props.style &&
    props.style.height &&
    typeof props.style.height !== 'number',
  'Invalid style: height. Height needs to be a number. Percentages or other values are not supported.'
)

const modeCheck = new PropCheck(
  props =>
    props && props.mode && !['datetime', 'date', 'time'].includes(props.mode),
  "Invalid mode. Valid modes: 'datetime', 'date', 'time'"
)

const checks = [widthCheck, heightCheck, modeCheck]