full_form.js

import React from "react"
class Form extends React.Component {
  state = {
    cats: [{name:"", age:""}],
    owner: "",
    description: ""
  }
handleChange = (e) => {
    if (["name", "age"].includes(e.target.className) ) {
      let cats = [...this.state.cats]
      cats[e.target.dataset.id][e.target.className] = e.target.value.toUpperCase()
      this.setState({ cats }, () => console.log(this.state.cats))
    } else {
      this.setState({ [e.target.name]: e.target.value.toUpperCase() })
    }
  }
addCat = (e) => {
    this.setState((prevState) => ({
      cats: [...prevState.cats, {name:"", age:""}],
    }));
  }
handleSubmit = (e) => { e.preventDefault() }
render() {
    let {owner, description, cats} = this.state
    return (
      <form onSubmit={this.handleSubmit} onChange={this.handleChange} >
        <label htmlFor="name">Owner</label> 
        <input type="text" name="owner" id="owner" value={owner} />
        <label htmlFor="description">Description</label> 
        <input type="text" name="description" id="description" value={description} />
        <button onClick={this.addCat}>Add new cat</button>
        {
          cats.map((val, idx)=> {
            let catId = `cat-${idx}`, ageId = `age-${idx}`
            return (
              <div key={idx}>
                <label htmlFor={catId}>{`Cat #${idx + 1}`}</label>
                <input
                  type="text"
                  name={catId}
                  data-id={idx}
                  id={catId}
                  value={cats[idx].name} 
                  className="name"
                />
                <label htmlFor={ageId}>Age</label>
                <input
                  type="text"
                  name={ageId}
                  data-id={idx}
                  id={ageId}
                  value={cats[idx].age} 
                  className="age"
                />
              </div>
            )
          })
        }
        <input type="submit" value="Submit" /> 
      </form>
    )
  }
}
export default Form