I'm using this example to set the height of the textarea.

but the size of the textarea is not set automatically if the textarea has a value.

https://codesandbox.io/s/autosize-textarea-forked-wdowvr?file=/src/App.tsx

import { useRef, useState } from "react";

import "./styles.css";

export default function App() {
  const [value, setValue] = useState("");
  const textAreaRef = useRef<HTMLTextAreaElement>(null);

  const handleChange = (evt) => {
    const val = evt.target?.value;

    setValue(val);
  };

  return (
    <div className="App">
      <label htmlFor="review-text">Review:</label>
      <textarea
        id="review-text"
        onChange={handleChange}
        onInput={(e: React.FormEvent<HTMLTextAreaElement>) => {
          e.currentTarget.style.height = e.currentTarget.scrollHeight   "px";
        }}
        ref={textAreaRef}
        rows={1}
        value={value}
      />
    </div>
  );
}

for example

how can i fix this issue?

CodePudding user response：

You can use the following snippets to adjust the height on loading the component.

Just for demo purposes:

const [value, setValue] = useState(
  "already has a value with\nmore text\nand even more"
);
const textAreaRef = useRef<HTMLTextAreaElement>(null);

You can access the ref once it is set. useEffect will do the trick here.

useEffect(() => {
  if (textAreaRef && textAreaRef.current) {
    textAreaRef.current.style.height = textAreaRef.current.scrollHeight   'px';
  }
}, []);

https://codesandbox.io/s/autosize-textarea-forked-symr7p?file=/src/App.tsx

CodePudding user response：

You also need to set the height once the DOM is mounted. This way it can respond to whatever value is in there before any user input.
I did this with the useEffect hook. (Don't forget to import it from react).

I also tweaked the method of changing the height a bit, because it wasn't working properly.

import { useRef, useState, useEffect } from "react";

import "./styles.css";

export default function App() {
  const [value, setValue] = useState("");
  const textAreaRef = useRef<HTMLTextAreaElement>(null);

  const handleChange = (evt) => {
    const val = evt.target?.value;

    setValue(val);
  };

  const resizeTextarea = (t: HTMLTextAreaElement) => {
    t.style.height = "auto";
    const p = parseFloat(window.getComputedStyle(t, null).getPropertyValue("padding-top")) 
              parseFloat(window.getComputedStyle(t, null).getPropertyValue("padding-bottom"));
    t.style.height = t.scrollHeight - p   "px";
  }

  const handleInput = (e: React.FormEvent<HTMLTextAreaElement>) => {
    resizeTextarea(e.currentTarget);
  }

  useEffect(() => {
    const t = textAreaRef.current;
    if (t != null) {
      t.style.overflowY = 'hidden';
      resizeTextarea(t);
    }
 },[]);

  return (
    <div className="App">
      <label htmlFor="review-text">Review:</label>
      <textarea
        id="review-text"
        onChange={handleChange}
        onInput={handleInput}
        ref={textAreaRef}
        rows={1}
        value={value}
      />
    </div>
  );
}

https://codesandbox.io/s/autosize-textarea-forked-s39ur2?file=/src/App.tsx:0-1172