---
title: "Search in a 'DT' table w/ or w/o a regular expression"
author: "Stéphane Laurent"
date: '2022-07-03'
tags: R, datatables, javascript
rbloggers: yes
output:
  md_document:
    variant: markdown
    preserve_yaml: true
  html_document:
    highlight: kate
    keep_md: no
highlighter: pandoc-solarized
---

It is possible to search in a 'DT' table with a regular expression:

``` {.r .numberLines}
datatable(
  data = dat,
  options = list(
    search = list(regex = TRUE)
  )
)
```

But it could be desirable to have the possibility to search either 
with a regular expression or with an ordinary string. 

The **SearchBuilder** extension allows to search in a table using 
numerous useful criteria, such as *"contains"*, *"starts with"*, 
*"ends with"*, etc:

``` {.r .numberLines}
library(DT)

dat <- iris[c(1:3, 51:53, 101:103), ]

datatable(
  dat,
  extensions = "SearchBuilder",
  options = list(
    dom = "Qlfrtip",
    searchBuilder = TRUE
  )
)
```

![](./figures/DT_SearchBuilder1.gif){width="65%"}

In general, this is enough. But if really needed, it is possible to add a 
custom search criterion. Here is how to add a *"matches regexp"* criterion, 
to search with a regular expression:

``` {.r .numberLines}
datatable(
  dat,
  extensions = "SearchBuilder",
  options = list(
    dom = "Qlfrtip",
    searchBuilder = list(
      conditions = list(
        string = list(
          regexp = list(
            conditionName = "Matches Regexp",
            init = JS(
              "function (that, fn, preDefined = null) {",
              "  var el = $('<input/>').on('input', function() {",
              "    fn(that, this);",
              "   });",
              "  if (preDefined !== null) {",
              "     $(el).val(preDefined[0]);",
              "  }",
              "  return el;",
              "}"
            ),
            inputValue = JS(
              "function (el) {",
              "  return $(el[0]).val();",
              "}"
            ),
            isInputValid = JS(
              "function (el, that) {",
              "  var regexp = $(el[0]).val();",
              "  var valid = true;",
              "  try {",
              "    new RegExp(regexp, 'g');",
              "  } catch(e) {",
              "    valid = false;",
              "  }",
              "  return valid;",
              "}"
            ),
            search = JS(
              "function (value, regexp) {",
              "  var reg = new RegExp(regexp, 'g');",
              "  return reg.test(value);",
              "}"
            )
          )
        )
      )
    )
  )
)
```

![](./figures/DT_SearchBuilder2.gif){width="65%"}