Use unary operators to make code cleaner

Author: 1011zaozao-max

index.js

@@ -12,18 +12,16 @@ export default class TinyQueue {
 
     push(item) {
         this.data.push(item);
-        this.length++;
-        this._up(this.length - 1);
+        this._up(this.length++);
     }
 
     pop() {
         if (this.length === 0) return undefined;
 
         const top = this.data[0];
         const bottom = this.data.pop();
-        this.length--;
 
-        if (this.length > 0) {
+        if (--this.length > 0) {
             this.data[0] = bottom;
             this._down(0);
         }