update

Author: munnaSorder

concat.js

@@ -0,0 +1,11 @@
+
+function join(arr, sp = ',') {
+    let newString = '';
+    for (let i = 0, length = arr.length; i < length; i++) {
+        if ((i+1) === arr.length) newString = newString + arr[i] + sp;
+        else newString = newString + arr[i];
+    }
+    return newString;
+}
+
+console.log(join([1,2,3,4,5,6], ' '))