ember-template-lint/lib/rules/template-length.js

Linter for Ember or Handlebars templates.

import createErrorMessage from '../helpers/create-error-message.js';
import Rule from './_base.js';

/*
 Enforce template size constraints

 The following values are valid configuration:

   * boolean -- `true` for enabled (defaults of max: 200 / min: 5) / `false` for disabling this rule
   * object --
     * max {number} - the longest a template should be without failing a test (assuming the
       right thing to do would be to split the template up into pieces).
     * min {number} - the shortest a template should be without failing a test (assuming the
       right thing to do would be to inline the template).
 */

const DEFAULT_MAX_LENGTH = 200;
const DEFAULT_MIN_LENGTH = 5;

const DEFAULT_CONFIG = {
  max: DEFAULT_MAX_LENGTH,
  min: DEFAULT_MIN_LENGTH,
};

function isValidConfigObjectFormat(config) {
  for (let key in config) {
    let value = config[key];
    let valueIsInteger = Number.isInteger(value);

    if (key === 'min' && !valueIsInteger) {
      return false;
    } else if (key === 'max' && !valueIsInteger) {
      return false;
    }
  }
  return true;
}

export default class TemplateLength extends Rule {
  parseConfig(config) {
    let configType = typeof config;

    switch (configType) {
      case 'boolean': {
        // if `true` use `DEFAULT_CONFIG`
        return config ? DEFAULT_CONFIG : {};
      }
      case 'object': {
        if (isValidConfigObjectFormat(config)) {
          return config;
        }
        break;
      }
      case 'undefined': {
        return {};
      }
    }

    let errorMessage = createErrorMessage(
      this.ruleName,
      [
        '  * boolean - `true` to enable / `false` to disable',
        '  * object -- An object with the following keys:',
        '    * `min` -- Minimum length of a template',
        '    * `max` -- Maximum length of a template',
      ],
      config
    );

    throw new Error(errorMessage);
  }
  /**
   * @returns {import('./types.js').VisitorReturnType<TemplateLength>}
   */
  visitor() {
    return {
      Template: {
        // implementation goes here in exit(): in the exit handler, the rule will not
        // be called if it has been disabled by any inline comments within the file.

        exit(node) {
          if (this.config.max && this.source.length > this.config.max) {
            this.log({
              message: `Template length of ${this.source.length} exceeds ${this.config.max}`,
              node,
            });
          } else if (this.config.min && this.source.length < this.config.min) {
            this.log({
              message: `Template length of ${this.source.length} is smaller than ${this.config.min}`,
              node,
            });
          }
        },
      },
    };
  }
}