Question

我正在尝试根据用户按下下一个按钮来更改图像，但这没有发生

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;

public class Player : MonoBehaviour
{
    private Vector2 targetPos;
    public float Yincrement;

    public float speed;
    public float maxHeight;
    public float minHeigth;

    public int health = 3;
    public int numOfHearts;

    public Image[] hearts;
    public Sprite heartFull;
    public Sprite heartEmpty;

    public GameObject effect;

    public Image healthDisplay;

    private void Update()
    {
        for (int i = 0; i < hearts.Length; i++)
        {
            if (i < health)
            {
                hearts[i].sprite = heartFull;
            }
            else
            {
                hearts[i].sprite = heartEmpty;

                if (i < numOfHearts)
                {
                    hearts[i].enabled = true;
                }
                else
                {
                    hearts[i].enabled = false;
                }
            }
        }

        if (health <= 0)
        {
            SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);
        }

        if (Input.GetKeyDown(KeyCode.UpArrow) && transform.position.y < maxHeight)
        {
            transform.Translate(0,Yincrement,0)
        }
        else if (Input.GetKeyDown(KeyCode.DownArrow) && transform.position.y > minHeigth)
        {
            Instantiate(effect, transform.position, Quaternion.identity);

            transform.Translate(0,Yincrement,0);
        }
    }
}

var my_image = document.getElementById(main_image);

var image_array = ["https://www.w3schools.com/jsref/klematis2.jpg"];

var image_index = 1;

function change_image(){
	my_image.setAttribute("src", image_array[image_index]);
	image_index++;
	if(image_index > 1){image_index = 0;}
}

Answer 1

document.getElementById()需要在其中传递一个字符串。如果main_image是一个元素而不是字符串，则可能是您遇到的问题。

Answer 2

看起来您的数组索引设置错误

Answer 3

您的代码中有2个问题：

1- getElementByID需要一个字符串。 javascript认为main_image是变量名，而不是值。

2-您的数组只有一个元素，因此它的位置是0，而不是1。

下面的代码有效：

var my_image = document.getElementById("main_image");

var image_array = ["https://www.w3schools.com/jsref/klematis2.jpg"];

var image_index = 0;

function change_image(){
	my_image.setAttribute("src", image_array[image_index]);
	image_index++;
	if(image_index > 1){image_index = 0;}
}

<img src="https://www.w3schools.com/jsref/klematis.jpg" id ="main_image">

		<button onclick="change_image()"> next </button>

Answer 4

或者，您也可以查询选择器。其次，使用addEventListener代替按钮中的onClick。

` 让my_image = document.querySelector（“＃main_image”）;

let nextBtn = document.querySelector("button")
let image_array = ["https://www.w3schools.com/jsref/klematis2.jpg"];

let image_index = 0;

const change_image =() => {
my_image.setAttribute("src", image_array[image_index]);
image_index++;
if(image_index > 1){image_index = 0;}
}
nextBtn.addEventListener("click", change_image)

` 已经给出了答案，我只是在语法上改进了

Answer 5

将字符串传递到document.getElementById（）。我希望这对您有用。

图像在jQuery setAttribute中没有变化

5 个答案: