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WaitFor

Utility class for awaiting the existence of instances.

By default, all promises timeout after 60 seconds, unless the timeout argument is specified.

note

Promises will be rejected if the parent (or any ancestor) is unparented from the game.

Set name before parent

When waiting for instances based on name (e.g. WaitFor.Child), the WaitFor system is listening to events to capture these instances being added. This means that the name must be set before being parented into the object.

Properties​

Error​

</>
WaitFor.Error: {
Unparented: string,
ParentChanged: string
}

Functions​

Child​

</>
WaitFor.Child(
parent: Instance,
childName: string,
timeout: number?
) → Promise<Instance>

Wait for a child to exist within a given parent based on the child name.

WaitFor.Child(parent, "SomeObject"):andThen(function(someObject)
	print(someObject, "now exists")
end):catch(warn)

Children​

</>
WaitFor.Children(
parent: Instance,
childrenNames: {string},
timeout: number?
) → Promise<{Instance}>

Wait for all children to exist within the given parent.

WaitFor.Children(parent, {"SomeObject01", "SomeObject02"}):andThen(function(children)
	local someObject01, someObject02 = table.unpack(children)
end)
note

Once all children are found, a second check is made to ensure that all children are still directly parented to the given parent (since one child's parent might have changed before another child was found). A rejected promise with the WaitFor.Error.ParentChanged error will be thrown if any parents of the children no longer match the given parent.

Descendant​

</>
WaitFor.Descendant(
parent: Instance,
descendantName: string,
timeout: number?
) → Promise<Instance>

Wait for a descendant to exist within a given parent. This is similar to WaitFor.Child, except it looks for all descendants instead of immediate children. 

WaitFor.Descendant(parent, "SomeDescendant"):andThen(function(someDescendant)
	print("SomeDescendant now exists")
end)

Descendants​

</>
WaitFor.Descendants(
parent: Instance,
descendantNames: {string},
timeout: number?
) → Promise<{Instance}>

Wait for all descendants to exist within a given parent.

WaitFor.Descendants(parent, {"SomeDescendant01", "SomeDescendant02"}):andThen(function(descendants)
	local someDescendant01, someDescendant02 = table.unpack(descendants)
end)
note

Once all descendants are found, a second check is made to ensure that none of the instances have moved outside of the parent (since one instance might change before another instance is found). A rejected promise with the WaitFor.Error.ParentChanged error will be thrown if any of the instances are no longer descendants of the given parent.

PrimaryPart​

</>
WaitFor.PrimaryPart(
model: Model,
timeout: number?
) → Promise<Instance>

Wait for the PrimaryPart of a model to exist.

WaitFor.PrimaryPart(model):andThen(function(primaryPart)
	print(primaryPart == model.PrimaryPart)
end)

ObjectValue​

</>
WaitFor.ObjectValue(
objectValue: ObjectValue,
timeout: number?
) → Promise<Instance>

Wait for the Value of an ObjectValue to exist.

WaitFor.ObjectValue(someObjectValue):andThen(function(value)
	print("someObjectValue's value is", value)
end)

Custom​

</>
WaitFor.Custom(
predicate: () → T?,
timeout: number?
) → Promise<T>

Wait for the given predicate function to return a non-nil value of of type T. The predicate is fired every RunService Heartbeat step. 

-- Example, waiting for some property to be set:
WaitFor.Custom(function() return vectorForce.Attachment0 end):andThen(function(a0)
	print(a0)
end)
Show raw api
{
    "functions": [
        {
            "name": "Child",
            "desc": "Wait for a child to exist within a given parent based on the child name.\n\n```lua\nWaitFor.Child(parent, \"SomeObject\"):andThen(function(someObject)\n\tprint(someObject, \"now exists\")\nend):catch(warn)\n```",
            "params": [
                {
                    "name": "parent",
                    "desc": "",
                    "lua_type": "Instance"
                },
                {
                    "name": "childName",
                    "desc": "",
                    "lua_type": "string"
                },
                {
                    "name": "timeout",
                    "desc": "",
                    "lua_type": "number?"
                }
            ],
            "returns": [
                {
                    "desc": "",
                    "lua_type": "Promise<Instance>"
                }
            ],
            "function_type": "static",
            "source": {
                "line": 61,
                "path": "modules/wait-for/init.lua"
            }
        },
        {
            "name": "Children",
            "desc": "Wait for all children to exist within the given parent.\n\n```lua\nWaitFor.Children(parent, {\"SomeObject01\", \"SomeObject02\"}):andThen(function(children)\n\tlocal someObject01, someObject02 = table.unpack(children)\nend)\n```\n\n:::note\nOnce all children are found, a second check is made to ensure that all children\nare still directly parented to the given `parent` (since one child's parent\nmight have changed before another child was found). A rejected promise with the\n`WaitFor.Error.ParentChanged` error will be thrown if any parents of the children\nno longer match the given `parent`.\n:::",
            "params": [
                {
                    "name": "parent",
                    "desc": "",
                    "lua_type": "Instance"
                },
                {
                    "name": "childrenNames",
                    "desc": "",
                    "lua_type": "{ string }"
                },
                {
                    "name": "timeout",
                    "desc": "",
                    "lua_type": "number?"
                }
            ],
            "returns": [
                {
                    "desc": "",
                    "lua_type": "Promise<{Instance}>"
                }
            ],
            "function_type": "static",
            "source": {
                "line": 92,
                "path": "modules/wait-for/init.lua"
            }
        },
        {
            "name": "Descendant",
            "desc": "Wait for a descendant to exist within a given parent. This is similar to\n`WaitFor.Child`, except it looks for all descendants instead of immediate\nchildren.\n\n```lua\nWaitFor.Descendant(parent, \"SomeDescendant\"):andThen(function(someDescendant)\n\tprint(\"SomeDescendant now exists\")\nend)\n```",
            "params": [
                {
                    "name": "parent",
                    "desc": "",
                    "lua_type": "Instance"
                },
                {
                    "name": "descendantName",
                    "desc": "",
                    "lua_type": "string"
                },
                {
                    "name": "timeout",
                    "desc": "",
                    "lua_type": "number?"
                }
            ],
            "returns": [
                {
                    "desc": "",
                    "lua_type": "Promise<Instance>"
                }
            ],
            "function_type": "static",
            "source": {
                "line": 120,
                "path": "modules/wait-for/init.lua"
            }
        },
        {
            "name": "Descendants",
            "desc": "Wait for all descendants to exist within a given parent.\n\n```lua\nWaitFor.Descendants(parent, {\"SomeDescendant01\", \"SomeDescendant02\"}):andThen(function(descendants)\n\tlocal someDescendant01, someDescendant02 = table.unpack(descendants)\nend)\n```\n\n:::note\nOnce all descendants are found, a second check is made to ensure that none of the\ninstances have moved outside of the parent (since one instance might change before\nanother instance is found). A rejected promise with the `WaitFor.Error.ParentChanged`\nerror will be thrown if any of the instances are no longer descendants of the given\n`parent`.\n:::",
            "params": [
                {
                    "name": "parent",
                    "desc": "",
                    "lua_type": "Instance"
                },
                {
                    "name": "descendantNames",
                    "desc": "",
                    "lua_type": "{ string }"
                },
                {
                    "name": "timeout",
                    "desc": "",
                    "lua_type": "number?"
                }
            ],
            "returns": [
                {
                    "desc": "",
                    "lua_type": "Promise<{Instance}>"
                }
            ],
            "function_type": "static",
            "source": {
                "line": 151,
                "path": "modules/wait-for/init.lua"
            }
        },
        {
            "name": "PrimaryPart",
            "desc": "Wait for the PrimaryPart of a model to exist.\n\n```lua\nWaitFor.PrimaryPart(model):andThen(function(primaryPart)\n\tprint(primaryPart == model.PrimaryPart)\nend)\n```",
            "params": [
                {
                    "name": "model",
                    "desc": "",
                    "lua_type": "Model"
                },
                {
                    "name": "timeout",
                    "desc": "",
                    "lua_type": "number?"
                }
            ],
            "returns": [
                {
                    "desc": "",
                    "lua_type": "Promise<Instance>"
                }
            ],
            "function_type": "static",
            "source": {
                "line": 177,
                "path": "modules/wait-for/init.lua"
            }
        },
        {
            "name": "ObjectValue",
            "desc": "Wait for the Value of an ObjectValue to exist.\n\n```lua\nWaitFor.ObjectValue(someObjectValue):andThen(function(value)\n\tprint(\"someObjectValue's value is\", value)\nend)\n```",
            "params": [
                {
                    "name": "objectValue",
                    "desc": "",
                    "lua_type": "ObjectValue"
                },
                {
                    "name": "timeout",
                    "desc": "",
                    "lua_type": "number?"
                }
            ],
            "returns": [
                {
                    "desc": "",
                    "lua_type": "Promise<Instance>"
                }
            ],
            "function_type": "static",
            "source": {
                "line": 205,
                "path": "modules/wait-for/init.lua"
            }
        },
        {
            "name": "Custom",
            "desc": "Wait for the given predicate function to return a non-nil value of\nof type `T`. The predicate is fired every RunService Heartbeat step.\n\n```lua\n-- Example, waiting for some property to be set:\nWaitFor.Custom(function() return vectorForce.Attachment0 end):andThen(function(a0)\n\tprint(a0)\nend)\n```",
            "params": [
                {
                    "name": "predicate",
                    "desc": "",
                    "lua_type": "() -> T?"
                },
                {
                    "name": "timeout",
                    "desc": "",
                    "lua_type": "number?"
                }
            ],
            "returns": [
                {
                    "desc": "",
                    "lua_type": "Promise<T>"
                }
            ],
            "function_type": "static",
            "source": {
                "line": 235,
                "path": "modules/wait-for/init.lua"
            }
        }
    ],
    "properties": [
        {
            "name": "Error",
            "desc": "",
            "lua_type": "{Unparented: string, ParentChanged: string}",
            "source": {
                "line": 35,
                "path": "modules/wait-for/init.lua"
            }
        }
    ],
    "types": [],
    "name": "WaitFor",
    "desc": "Utility class for awaiting the existence of instances.\n\nBy default, all promises timeout after 60 seconds, unless the `timeout`\nargument is specified.\n\n:::note\nPromises will be rejected if the parent (or any ancestor) is unparented\nfrom the game.\n:::\n\n:::caution Set name before parent\nWhen waiting for instances based on name (e.g. `WaitFor.Child`), the `WaitFor`\nsystem is listening to events to capture these instances being added. This\nmeans that the name must be set _before_ being parented into the object.\n:::",
    "source": {
        "line": 29,
        "path": "modules/wait-for/init.lua"
    }
}