chore: replace deprecated String.prototype.substr() (#4343)

Author: CommanderRoot

client-src/utils/createSocketURL.js

@@ -5,7 +5,7 @@
 function format(objURL) {
   let protocol = objURL.protocol || "";
 
-  if (protocol && protocol.substr(-1) !== ":") {
+  if (protocol && !protocol.endsWith(":")) {
     protocol += ":";
   }
 

client-src/utils/parseURL.js

@@ -9,7 +9,7 @@ function parseURL(resourceQuery) {
   let options = {};
 
   if (typeof resourceQuery === "string" && resourceQuery !== "") {
-    const searchParams = resourceQuery.substr(1).split("&");
+    const searchParams = resourceQuery.slice(1).split("&");
 
     for (let i = 0; i < searchParams.length; i++) {
       const pair = searchParams[i].split("=");

test/e2e/range-header.test.js

@@ -42,7 +42,7 @@ describe("'Range' header", () => {
     );
     expect(responseRange.headers["content-length"]).toBe("500");
     expect(responseRange.headers["content-range"]).toMatch(/^bytes 0-499\//);
-    expect(responseRange.text).toBe(responseContent.substr(0, 500));
+    expect(responseRange.text).toBe(responseContent.slice(0, 500));
     expect(responseRange.text.length).toBe(500);
   });