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{"version":3,"file":"live.js","sources":["../src/directives/live.ts"],"sourcesContent":["/**\n * @license\n * Copyright 2020 Google LLC\n * SPDX-License-Identifier: BSD-3-Clause\n */\n\nimport {AttributePart, noChange, nothing} from '../lit-html.js';\nimport {\n directive,\n Directive,\n DirectiveParameters,\n PartInfo,\n PartType,\n} from '../directive.js';\nimport {isSingleExpression, setCommittedValue} from '../directive-helpers.js';\n\nclass LiveDirective extends Directive {\n constructor(partInfo: PartInfo) {\n super(partInfo);\n if (\n !(\n partInfo.type === PartType.PROPERTY ||\n partInfo.type === PartType.ATTRIBUTE ||\n partInfo.type === PartType.BOOLEAN_ATTRIBUTE\n )\n ) {\n throw new Error(\n 'The `live` directive is not allowed on child or event bindings'\n );\n }\n if (!isSingleExpression(partInfo)) {\n throw new Error('`live` bindings can only contain a single expression');\n }\n }\n\n render(value: unknown) {\n return value;\n }\n\n override update(part: AttributePart, [value]: DirectiveParameters<this>) {\n if (value === noChange || value === nothing) {\n return value;\n }\n const element = part.element;\n const name = part.name;\n\n if (part.type === PartType.PROPERTY) {\n // eslint-disable-next-line @typescript-eslint/no-explicit-any\n if (value === (element as any)[name]) {\n return noChange;\n }\n } else if (part.type === PartType.BOOLEAN_ATTRIBUTE) {\n if (!!value === element.hasAttribute(name)) {\n return noChange;\n }\n } else if (part.type === PartType.ATTRIBUTE) {\n if (element.getAttribute(name) === String(value)) {\n return noChange;\n }\n }\n // Resets the part's value, causing its dirty-check to fail so that it\n // always sets the value.\n setCommittedValue(part);\n return value;\n }\n}\n\n/**\n * Checks binding values against live DOM values, instead of previously bound\n * values, when determining whether to update the value.\n *\n * This is useful for cases where the DOM value may change from outside of\n * lit-html, such as with a binding to an `<input>` element's `value` property,\n * a content editable elements text, or to a custom element that changes it's\n * own properties or attributes.\n *\n * In these cases if the DOM value changes, but the value set through lit-html\n * bindings hasn't, lit-html won't know to update the DOM value and will leave\n * it alone. If this is not what you want--if you want to overwrite the DOM\n * value with the bound value no matter what--use the `live()` directive:\n *\n * ```js\n * html`<input .value=${live(x)}>`\n * ```\n *\n * `live()` performs a strict equality check against the live DOM value, and if\n * the new value is equal to the live value, does nothing. This means that\n * `live()` should not be used when the binding will cause a type conversion. If\n * you use `live()` with an attribute binding, make sure that only strings are\n * passed in, or the binding will update every render.\n */\nexport const live = directive(LiveDirective);\n\n/**\n * The type of the class that powers this directive. Necessary for naming the\n * directive's return type.\n */\nexport type {LiveDirective};\n"],"names":["live","directive","Directive","constructor","partInfo","super","type","PartType","PROPERTY","ATTRIBUTE","BOOLEAN_ATTRIBUTE","Error","isSingleExpression","render","value","update","part","noChange","nothing","element","name","hasAttribute","getAttribute","String","setCommittedValue"],"mappings":";;;;;SA2FaA,EAAOC,EA3EpB,cAA4BC,EAC1BC,YAAYC,GAEV,GADAC,MAAMD,GAGFA,EAASE,OAASC,EAASC,UAC3BJ,EAASE,OAASC,EAASE,WAC3BL,EAASE,OAASC,EAASG,kBAG7B,MAAUC,MACR,kEAGJ,IAAKC,EAAmBR,GACtB,MAAUO,MAAM,uDAEnB,CAEDE,OAAOC,GACL,OAAOA,CACR,CAEQC,OAAOC,GAAsBF,IACpC,GAAIA,IAAUG,GAAYH,IAAUI,EAClC,OAAOJ,EAET,MAAMK,EAAUH,EAAKG,QACfC,EAAOJ,EAAKI,KAElB,GAAIJ,EAAKV,OAASC,EAASC,UAEzB,GAAIM,IAAWK,EAAgBC,GAC7B,OAAOH,OAEJ,GAAID,EAAKV,OAASC,EAASG,mBAChC,KAAMI,IAAUK,EAAQE,aAAaD,GACnC,OAAOH,OAEJ,GAAID,EAAKV,OAASC,EAASE,WAC5BU,EAAQG,aAAaF,KAAiBN,EAAPS,GACjC,OAAON,EAMX,OADAO,EAAkBR,GACXF,CACR"} |