@material-ui/core/es/FormHelperText/FormHelperText.js

React components that implement Google's Material Design.

import _extends from "@babel/runtime/helpers/builtin/extends";
import _objectWithoutProperties from "@babel/runtime/helpers/builtin/objectWithoutProperties";
import React from 'react';
import PropTypes from 'prop-types';
import classNames from 'classnames';
import withStyles from '../styles/withStyles';
export const styles = theme => ({
  root: {
    color: theme.palette.text.secondary,
    fontFamily: theme.typography.fontFamily,
    fontSize: theme.typography.pxToRem(12),
    textAlign: 'left',
    marginTop: theme.spacing.unit,
    lineHeight: '1em',
    minHeight: '1em',
    margin: 0,
    '&$error': {
      color: theme.palette.error.main
    },
    '&$disabled': {
      color: theme.palette.text.disabled
    }
  },
  error: {},
  disabled: {},
  marginDense: {
    marginTop: theme.spacing.unit / 2
  }
});

function FormHelperText(props, context) {
  const {
    classes,
    className: classNameProp,
    disabled: disabledProp,
    error: errorProp,
    margin: marginProp,
    component: Component
  } = props,
        other = _objectWithoutProperties(props, ["classes", "className", "disabled", "error", "margin", "component"]);

  const {
    muiFormControl
  } = context;
  let disabled = disabledProp;
  let error = errorProp;
  let margin = marginProp;

  if (muiFormControl) {
    if (typeof disabled === 'undefined') {
      disabled = muiFormControl.disabled;
    }

    if (typeof error === 'undefined') {
      error = muiFormControl.error;
    }

    if (typeof margin === 'undefined') {
      margin = muiFormControl.margin;
    }
  }

  const className = classNames(classes.root, {
    [classes.disabled]: disabled,
    [classes.error]: error,
    [classes.marginDense]: margin === 'dense'
  }, classNameProp);
  return React.createElement(Component, _extends({
    className: className
  }, other));
}

FormHelperText.propTypes = process.env.NODE_ENV !== "production" ? {
  /**
   * The content of the component.
   */
  children: PropTypes.node,

  /**
   * Override or extend the styles applied to the component.
   * See [CSS API](#css-api) below for more details.
   */
  classes: PropTypes.object.isRequired,

  /**
   * @ignore
   */
  className: PropTypes.string,

  /**
   * The component used for the root node.
   * Either a string to use a DOM element or a component.
   */
  component: PropTypes.oneOfType([PropTypes.string, PropTypes.func, PropTypes.object]),

  /**
   * If `true`, the helper text should be displayed in a disabled state.
   */
  disabled: PropTypes.bool,

  /**
   * If `true`, helper text should be displayed in an error state.
   */
  error: PropTypes.bool,

  /**
   * If `dense`, will adjust vertical spacing. This is normally obtained via context from
   * FormControl.
   */
  margin: PropTypes.oneOf(['dense'])
} : {};
FormHelperText.defaultProps = {
  component: 'p'
};
FormHelperText.contextTypes = {
  muiFormControl: PropTypes.object
};
export default withStyles(styles, {
  name: 'MuiFormHelperText'
})(FormHelperText);