minErr.js

'use strict';

/**
 * @description
 *
 * This object provides a utility for producing rich Error messages within
 * Angular. It can be called as follows:
 *
 * var exampleMinErr = minErr('example');
 * throw exampleMinErr('one', 'This {0} is {1}', foo, bar);
 *
 * The above creates an instance of minErr in the example namespace. The
 * resulting error will have a namespaced error code of example.one.  The
 * resulting error will replace {0} with the value of foo, and {1} with the
 * value of bar. The object is not restricted in the number of arguments it can
 * take.
 *
 * If fewer arguments are specified than necessary for interpolation, the extra
 * interpolation markers will be preserved in the final string.
 *
 * Since data will be parsed statically during a build step, some restrictions
 * are applied with respect to how minErr instances are created and called.
 * Instances should have names of the form namespaceMinErr for a minErr created
 * using minErr('namespace') . Error codes, namespaces and template strings
 * should all be static strings, not variables or general expressions.
 *
 * @param {string} module The namespace to use for the new minErr instance.
 * @returns {function(code:string, template:string, ...templateArgs): Error} minErr instance
 */

function minErr(module) {
  return function () {
    var code = arguments[0],
      prefix = '[' + (module ? module + ':' : '') + code + '] ',
      template = arguments[1],
      templateArgs = arguments,
      stringify = function (obj) {
        if (typeof obj === 'function') {
          return obj.toString().replace(/ \{[\s\S]*$/, '');
        } else if (typeof obj === 'undefined') {
          return 'undefined';
        } else if (typeof obj !== 'string') {
          return JSON.stringify(obj);
        }
        return obj;
      },
      message, i;

    message = prefix + template.replace(/\{\d+\}/g, function (match) {
      var index = +match.slice(1, -1), arg;

      if (index + 2 < templateArgs.length) {
        arg = templateArgs[index + 2];
        if (typeof arg === 'function') {
          return arg.toString().replace(/ ?\{[\s\S]*$/, '');
        } else if (typeof arg === 'undefined') {
          return 'undefined';
        } else if (typeof arg !== 'string') {
          return toJson(arg);
        }
        return arg;
      }
      return match;
    });

    message = message + '\nhttp://errors.angularjs.org/"NG_VERSION_FULL"/' +
      (module ? module + '/' : '') + code;
    for (i = 2; i < arguments.length; i++) {
      message = message + (i == 2 ? '?' : '&') + 'p' + (i-2) + '=' +
        encodeURIComponent(stringify(arguments[i]));
    }

    return new Error(message);
  };
}