diff --git "a/\351\203\221\351\271\217\347\250\213/2\346\234\21021\346\227\245/demo.js" "b/\351\203\221\351\271\217\347\250\213/2\346\234\21021\346\227\245/demo.js"
new file mode 100644
index 0000000000000000000000000000000000000000..113c1d5b8aaad759247d34443cfa80657dc53116
--- /dev/null
+++ "b/\351\203\221\351\271\217\347\250\213/2\346\234\21021\346\227\245/demo.js"
@@ -0,0 +1,20 @@
+let fs = require("fs");
+let str = "bsvqhjsgvcbasdhb169823746198726bkjasbc你jhbsvqhjsgvcbasdhb169823746198726bkjasbcjh45dkjhciqu789jftxhrf";
+let fd = fs.openSync("./bigFile.txt", "a");
+for (let i = 0; i < 100000; i++) {
+    fs.writeSync(fd, String(str.substring(parseInt(Math.random() * 100), parseInt(Math.random() * 100))));
+}
+fs.closeSync(fd);
+let stream = fs.createReadStream("./bigFile.txt"), arr = Array();
+stream.on("data", (chunk) => {
+    for (let i = 0; i < chunk.toString().length; i++) {
+        var s = chunk.toString()[i] + "=";
+        arr[s] > 0 ? arr[s]++ : arr[s] = 1;
+    }
+})
+stream.on("end", () => {
+    console.log(((max = { name: null, num: 0 }) => {
+        for (const key in arr) {if (arr[key] > max.num) { max.name = key.slice(0, 1); max.num = arr[key] }}
+        return max;
+    })())
+})
\ No newline at end of file