Added a rate limiter

api.js

@@ -1,13 +1,20 @@
-const { default: axios } = require('axios')
+const axios = require('axios')
+const { RateLimiter } = require('limiter')
 
 class Api {
   constructor () {
     this.baseUrl = 'https://api.warframe.market/v1/'
-    this.timeout = 0
+    this.delay = process.env.API_DELAY ?? 3000
+    this.limiter = new RateLimiter({ tokensPerInterval: 1, interval: Number(this.delay) })
+  }
+
+  async _get (url) {
+    await this.limiter.removeTokens(1)
+    return axios.get(url)
   }
 
   async getOrders (url) {
-    const response = await axios.get(this.baseUrl + 'items/' + url + '/orders')
+    const response = await this._get(this.baseUrl + 'items/' + url + '/orders')
     return response.data.payload.orders.filter(function (order) {
       return order.order_type === 'sell' && order.user.status !== 'offline'
     })