IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.

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Using JavaScript in Elasticsearch

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Using JavaScript in Elasticsearch

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Once the plugin has been installed, JavaScript can be used at a scripting language by setting the lang parameter to javascript.

Scripting is available in many APIs, but we will use an example with the function_score for demonstration purposes:

Inline scripts

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Enabling inline scripting on an unprotected Elasticsearch cluster is dangerous. See File scripts for a safer option.

If you have enabled inline scripts, you can use JavaScript as follows:

PUT test/doc/1
{
  "num": 1.0
}

PUT test/doc/2
{
  "num": 2.0
}

GET test/_search
{
  "query": {
    "function_score": {
      "script_score": {
        "script": {
          "inline": "doc[\"num\"].value * factor",
          "lang": "javascript",
          "params": {
            "factor": 2
          }
        }
      }
    }
  }
}

Stored scripts

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Enabling stored scripts on an unprotected Elasticsearch cluster is dangerous. See File scripts for a safer option.

If you have enabled stored scripts, you can use JavaScript as follows:

PUT test/doc/1
{
  "num": 1.0
}

PUT test/doc/2
{
  "num": 2.0
}

POST _scripts/javascript/my_script  
{
  "script": "doc[\"num\"].value * factor"
}

GET test/_search
{
  "query": {
    "function_score": {
      "script_score": {
        "script": {
          "stored": "my_script", 
          "lang": "javascript",
          "params": {
            "factor": 2
          }
        }
      }
    }
  }
}

	We store the script under the id `my_script`.
	The function score query retrieves the script with id `my_script`.

File scripts

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You can save your scripts to a file in the config/scripts/ directory on every node. The .javascript file suffix identifies the script as containing JavaScript:

First, save this file as config/scripts/my_script.js on every node in the cluster:

doc["num"].value * factor

then use the script as follows:

PUT test/doc/1
{
  "num": 1.0
}

PUT test/doc/2
{
  "num": 2.0
}

GET test/_search
{
  "query": {
    "function_score": {
      "script_score": {
        "script": {
          "file": "my_script", 
          "lang": "javascript",
          "params": {
            "factor": 2
          }
        }
      }
    }
  }
}

The function score query retrieves the script with filename my_script.javascript.

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