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docs/ccxt/wiki/examples/js/fetch-all-tickers-to-files.md

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+- [Fetch All Tickers To Files](./examples/js/)
+
+
+ ```javascript
+ 
+
+import ccxt from '../../js/ccxt.js';
+import ololog from 'ololog';
+
+const { noLocate } = ololog;
+const log = noLocate;
+
+import fs from 'fs';
+
+// the numWorkers constant defines the number of concurrent workers
+// those aren't really threads in terms of the async environment
+// set this to the number of cores in your CPU * 2
+// or play with this number to find a setting that works best for you
+
+const numWorkers = 8;(async () => {
+
+    // make an array of all exchanges
+    const exchanges = ccxt.exchanges
+
+        // filter coinmarketcap and theocean
+        // coinmarketcap isn't really an exchange
+        // theocean requires web3 dependencies to be installed
+
+        .filter (id => ![ 'coinmarketcap', 'theocean' ].includes (id))
+
+        // instantiate each exchange and save it to the exchanges list
+
+        .map (id => new ccxt[id] ())
+
+    // the worker function for each "async thread"
+    const worker = async function () {
+
+        // while the array of all exchanges is not empty
+        while (exchanges.length > 0) {
+
+            // pop one exchange from the array
+            const exchange = exchanges.pop ()
+
+            // check if it has the necessary method implemented
+            if (exchange.has['fetchTickers']) {
+
+                // try to do "the work" and handle errors if any
+                try {
+
+                    // fetch the response for all tickers from the exchange
+                    const tickers = await exchange.fetchTickers ()
+
+                    // make a filename from exchange id
+                    const filename = exchange.id + '.json'
+
+                    // save the response to a file
+                    fs.writeFileSync (filename, JSON.stringify ({ tickers }));
+
+                    // print out a message on success
+                    log.green (exchange.id, 'tickers saved to', filename)
+
+                } catch (e) {
+
+                    // in case of error - print it out and ignore it further
+                    log.red (e.constructor.name, e.message)
+                }
+
+            } else {
+
+                log.red (exchange.id, "has['fetchTickers'] = false");
+            }
+        }
+    }
+
+    // create numWorkers "threads" (they aren't really threads)
+    const workers = [ ... Array (numWorkers) ].map (_ => worker ())
+
+    // wait for all of them to execute or fail
+    await Promise.all (workers)
+
+}) ()
+ 
+```