如何使用 api 转到下一页？

Question

hello everyone i am new to javascript. I'm having a problem with the API, can you help me? Thank you from now.

api_url is not updating for index. Next page 2,3,4 It isn't happening. But accepts 1...

 var index = 1; const main = document.getElementById("main"); const API_URL =  "https://api.themoviedb.org/3/discover/movie?sort_by=popularity.desc&api_key=xxxxxxxxxxxxxxxxxxxx&page=" + index; next.addEventListener("click", () => { index = index + 1; getMovies(API_URL); }); prev.addEventListener("click", () => { if (index == 1 || index == 0) { alert("not working"); } else { index = index - 1; getMovies( "https://api.themoviedb.org/3/discover/movie?sort_by=popularity.desc&api_key=xxxxxxxxxxxxxxxxxxxxx&page=" + index ); } });

This is working. But How does the above work?

 var index = 1; const main = document.getElementById("main"); const API_URL =  "https://api.themoviedb.org/3/discover/movie?sort_by=popularity.desc&api_key=xxxxxxxxxxxxxxxxxxxx&page=" + index; next.addEventListener("click", () => { index = index + 1; getMovies( "https://api.themoviedb.org/3/discover/movie?sort_by=popularity.desc&api_key=xxxxxxxxxxxxxxxxxxxxx&page=" + index ); }); prev.addEventListener("click", () => { if (index == 1 || index == 0) { alert("not working"); } else { index = index - 1; getMovies( "https://api.themoviedb.org/3/discover/movie?sort_by=popularity.desc&api_key=xxxxxxxxxxxxxxxxxxxxx&page=" + index ); } });

Answer 1

The first example is not working because API_URL is a const, so it wont change. You should try using a let.

var index = 1;
const main = document.getElementById("main");
let API_URL =
  "https://api.themoviedb.org/3/discover/movie?sort_by=popularity.desc&api_key=xxxxxxxxxxxxxxxxxxxx&page=" + index;

next.addEventListener("click", () => {
  index = index + 1;
  getMovies(API_URL);
});

prev.addEventListener("click", () => {
  if (index == 1 || index == 0) {
    alert("not working");
  } else {
    index = index - 1;
    getMovies(
      "https://api.themoviedb.org/3/discover/movie?sort_by=popularity.desc&api_key=xxxxxxxxxxxxxxxxxxxxx&page=" + index
    );
  }
});