> For the complete documentation index, see [llms.txt](https://fivesobes.gitbook.io/nexorm/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://fivesobes.gitbook.io/nexorm/operators/update-operators/array-operators/usdconcat.md).

# $concat

The $concat operation is used to merge multiple strings or arrays into a single string or array. When applied to strings, it joins them together without any separators. When used with arrays, it combines their elements into a single array while preserving the order. This operation is useful for dynamically constructing text values, merging lists of data, or appending new elements to an existing collection efficiently.

```typescript
await Member.$update({
    $where: { 
        age: { 
            $eq: 16 
        } 
    },
    $update: {
       $concat: {
         badges: ['MODERATOR']
       }
    }
});
```