Improve typing (#2055)

src/utils.ts

@@ -90,23 +90,20 @@ export function removeElement<T>(
     array: T[],
     fn: (t: T, i?: number, a?: T[]) => boolean,
     reverse?: boolean,
-) {
-    let i;
-    let removed;
+): boolean {
+    let i: number;
     if (reverse) {
         for (i = array.length - 1; i >= 0; i--) {
             if (fn(array[i], i, array)) {
-                removed = array[i];
                 array.splice(i, 1);
-                return removed;
+                return true;
             }
         }
     } else {
         for (i = 0; i < array.length; i++) {
             if (fn(array[i], i, array)) {
-                removed = array[i];
                 array.splice(i, 1);
-                return removed;
+                return true;
             }
         }
     }
@@ -276,31 +273,6 @@ export function deepSortedObjectEntries(obj: any): [string, any][] {
     return pairs;
 }
 
-/**
- * Copy properties from one object to another.
- *
- * All enumerable properties, included inherited ones, are copied.
- *
- * This is approximately equivalent to ES6's Object.assign, except
- * that the latter doesn't copy inherited properties.
- *
- * @param {Object} target  The object that will receive new properties
- * @param {...Object} source  Objects from which to copy properties
- *
- * @return {Object} target
- */
-export function extend(...restParams) {
-    const target = restParams[0] || {};
-    for (let i = 1; i < restParams.length; i++) {
-        const source = restParams[i];
-        if (!source) continue;
-        for (const propName in source) { // eslint-disable-line guard-for-in
-            target[propName] = source[propName];
-        }
-    }
-    return target;
-}
-
 /**
  * Inherit the prototype methods from one constructor into another. This is a
  * port of the Node.js implementation with an Object.create polyfill.