invariant.js

/**
 * Copyright 2013-2015, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */

'use strict'

/**
 * Use invariant() to assert state which your program assumes to be true.
 *
 * Provide sprintf-style format (only %s is supported) and arguments
 * to provide information about what broke and what you were
 * expecting.
 *
 * The invariant message will be stripped in production, but the invariant
 * will remain to ensure logic does not differ in production.
 */

const invariant = (condition, format, a, b, c, d, e, f) => {
  const noFormat = typeof format === 'undefined'
  if (condition) {} else {
    let error
    if (noFormat) {
      error = new Error(
        'Minified exception occurred use the non-minified dev environment ' +
        'for the full error message and additional helpful warnings.'
      )
    } else {
      const args = [a, b, c, d, e, f]
      const argIndex = 0
      error = new Error(
        format.replace(/%s/g, () => args[argIndex++])
      )
      error.name = 'Invariant Violation'
    }

    error.framesToPop = 1 // we don't care about invariant's own frame
    throw error
  }

}

export default invariant