限制React中映射值的字符长度

{item.description} 到250个字符?

 import React from "react";

 const Component = props => {
  const classes = props.classes;
  return (
    <div className={classes.container}>
      <ul className={classes.items}>
        {props.children.map((item, i) => (
          <li key={i} className={classes.item}>
            <p className={classes.category}>
              {item.genre} {item.date}
            </p>
            <p className={classes.header}>{item.header}</p>
            <p className={classes.details}>{item.description}</p>
          </li>
        ))}
      </ul>
    </div>
  );
};