join.json

{
  "join": [
    {
      "expr": "join(github.event.issue.labels.*.name, ', ')",
      "contexts": {
        "github": {
          "event": {
            "issue": {
              "labels": [
                {
                  "name": "bug"
                },
                {
                  "name": "enhancement"
                },
                {
                  "name": "help wanted"
                }
              ]
            }
          }
        }
      },
      "result": { "kind": "String", "value": "bug, enhancement, help wanted" }
    },
    {
      "expr": "join(null)",
      "result": { "kind": "String", "value": "" }
    },
    {
      "expr": "join(true)",
      "result": { "kind": "String", "value": "true" }
    },
    {
      "expr": "join(123.456)",
      "result": { "kind": "String", "value": "123.456" }
    },
    {
      "expr": "join('abc')",
      "result": { "kind": "String", "value": "abc" }
    },
    {
      "expr": "join(myArray)",
      "contexts": { "myArray": [] },
      "result": { "kind": "String", "value": "" }
    },
    {
      "expr": "join(myObject)",
      "contexts": { "myObject": {} },
      "result": { "kind": "String", "value": "" }
    },
    {
      "expr": "join(myObject)",
      "contexts": { "myObject": { "key1": "value1" } },
      "result": { "kind": "String", "value": "" }
    },
    {
      "expr": "join(myArray)",
      "contexts": { "myArray": [ null, true, 123.456, "abc", [], ["def"], {}, { "key1": "value1" } ] },
      "result": { "kind": "String", "value": ",true,123.456,abc,Array,Array,Object,Object" }
    },
    {
      "expr": "join(myArray, null)",
      "contexts": { "myArray": [ "_ITEM-1_", "_ITEM-2_", "_ITEM-3_" ] },
      "result": { "kind": "String", "value": "_ITEM-1__ITEM-2__ITEM-3_" }
    },
    {
      "expr": "join(myArray, true)",
      "contexts": { "myArray": [ "_ITEM-1_", "_ITEM-2_", "_ITEM-3_" ] },
      "result": { "kind": "String", "value": "_ITEM-1_true_ITEM-2_true_ITEM-3_" }
    },
    {
      "expr": "join(myArray, 123.456)",
      "contexts": { "myArray": [ "_ITEM-1_", "_ITEM-2_", "_ITEM-3_" ] },
      "result": { "kind": "String", "value": "_ITEM-1_123.456_ITEM-2_123.456_ITEM-3_" }
    },
    {
      "expr": "join(myArray, ' | ')",
      "contexts": { "myArray": [ "_ITEM-1_", "_ITEM-2_", "_ITEM-3_" ] },
      "result": { "kind": "String", "value": "_ITEM-1_ | _ITEM-2_ | _ITEM-3_" }
    },
    {
      "expr": "join(myArray, mySeparator)",
      "contexts": {
        "myArray": [ "_ITEM-1_", "_ITEM-2_", "_ITEM-3_" ],
        "mySeparator": []
      },
      "result": { "kind": "String", "value": "_ITEM-1_,_ITEM-2_,_ITEM-3_" }
    },
    {
      "expr": "join(myArray, mySeparator)",
      "contexts": {
        "myArray": [ "_ITEM-1_", "_ITEM-2_", "_ITEM-3_" ],
        "mySeparator": {}
      },
      "result": { "kind": "String", "value": "_ITEM-1_,_ITEM-2_,_ITEM-3_" }
    },
    {
      "expr": "join()",
      "err": {
        "kind": "parsing",
        "value": "Too few parameters supplied: "
      }
    },
    {
      "expr": "join(1, 2, 3)",
      "err": {
        "kind": "parsing",
        "value": "Too many parameters supplied: "
      }
    }
  ]
}