使用dart创建一个javascript库 [英] Using dart to create a javascript library
本文介绍了使用dart创建一个javascript库的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我目前正在使用JavaScript库，为了减少错误的数量，我认为我的库可能从使用Dart的静态打字机制。首先，因为我的lib没有做任何互操作与HTML或其他JavaScript库，只有纯javascript对象操作的东西。但是我没有找到任何信息，显示如何可能使用dart构建一个JS库。所以我已经尝试做自己，创建初始的dart文件：
I'm currently working on a JavaScript library, and in order to reduce the amount of bugs I thought that my library might benefit from using Dart's static typing mechanism. First, because my lib wasn't doing any interop neither with HTML nor with other JavaScript libraries, only pure javascript object manipulation stuff. However I didn't find any info on the net showing how it is possible to build a JS library using dart. So I've tried to do that myself, created initial dart file:
library Repo;
class Type {
final String name;
final TypeCategory category;
Type(String name, TypeCategory category) : name = name, category = category {
category.types[name] = this;
}
}
class TypeCategory {
final String name;
final Map<String, Type> types = new Map();
TypeCategory(this.name);
}
class Branch {
}
class Descriptor {
}
class TableDescriptor extends Descriptor {
TableDescriptor.ctor() {
}
}
class Repo {
Descriptor descriptor(String name) {
}
Branch branch(String name) {
}
void Merge() {
}
}
main() {
return Repo;
}
使用dart2js编译它到JavaScript， p>
Compiled it to JavaScript using dart2js to see how I'm doing:
// Generated by dart2js, the Dart to JavaScript compiler version: 1.3.6.
// The code supports the following hooks:
// dartPrint(message):
// if this function is defined it is called instead of the Dart [print]
// method.
//
// dartMainRunner(main, args):
// if this function is defined, the Dart [main] method will not be invoked
// directly. Instead, a closure that will invoke [main], and its arguments
// [args] is passed to [dartMainRunner].
(function($) {
function dart(){ this.x = 0 }var A = new dart;
delete A.x;
var B = new dart;
delete B.x;
var C = new dart;
delete C.x;
var D = new dart;
delete D.x;
var E = new dart;
delete E.x;
var F = new dart;
delete F.x;
var G = new dart;
delete G.x;
var H = new dart;
delete H.x;
var J = new dart;
delete J.x;
var K = new dart;
delete K.x;
var L = new dart;
delete L.x;
var M = new dart;
delete M.x;
var N = new dart;
delete N.x;
var O = new dart;
delete O.x;
var P = new dart;
delete P.x;
var Q = new dart;
delete Q.x;
var R = new dart;
delete R.x;
var S = new dart;
delete S.x;
var T = new dart;
delete T.x;
var U = new dart;
delete U.x;
var V = new dart;
delete V.x;
var W = new dart;
delete W.x;
var X = new dart;
delete X.x;
var Y = new dart;
delete Y.x;
var Z = new dart;
delete Z.x;
function Isolate() {}
init();
$ = Isolate.$isolateProperties;
var $$ = {};
(function (reflectionData) {
"use strict";
function map(x){x={x:x};delete x.x;return x}
function processStatics(descriptor) {
for (var property in descriptor) {
if (!hasOwnProperty.call(descriptor, property)) continue;
if (property === "^") continue;
var element = descriptor[property];
var firstChar = property.substring(0, 1);
var previousProperty;
if (firstChar === "+") {
mangledGlobalNames[previousProperty] = property.substring(1);
var flag = descriptor[property];
if (flag > 0) descriptor[previousProperty].$reflectable = flag;
if (element && element.length) init.typeInformation[previousProperty] = element;
} else if (firstChar === "@") {
property = property.substring(1);
$[property]["@"] = element;
} else if (firstChar === "*") {
globalObject[previousProperty].$defaultValues = element;
var optionalMethods = descriptor.$methodsWithOptionalArguments;
if (!optionalMethods) {
descriptor.$methodsWithOptionalArguments = optionalMethods = {}
}
optionalMethods[property] = previousProperty;
} else if (typeof element === "function") {
globalObject[previousProperty = property] = element;
functions.push(property);
init.globalFunctions[property] = element;
} else if (element.constructor === Array) {
addStubs(globalObject, element, property, true, descriptor, functions);
} else {
previousProperty = property;
var newDesc = {};
var previousProp;
for (var prop in element) {
if (!hasOwnProperty.call(element, prop)) continue;
firstChar = prop.substring(0, 1);
if (prop === "static") {
processStatics(init.statics[property] = element[prop]);
} else if (firstChar === "+") {
mangledNames[previousProp] = prop.substring(1);
var flag = element[prop];
if (flag > 0) element[previousProp].$reflectable = flag;
} else if (firstChar === "@" && prop !== "@") {
newDesc[prop.substring(1)]["@"] = element[prop];
} else if (firstChar === "*") {
newDesc[previousProp].$defaultValues = element[prop];
var optionalMethods = newDesc.$methodsWithOptionalArguments;
if (!optionalMethods) {
newDesc.$methodsWithOptionalArguments = optionalMethods={}
}
optionalMethods[prop] = previousProp;
} else {
var elem = element[prop];
if (prop !== "^" && elem != null && elem.constructor === Array && prop !== "<>") {
addStubs(newDesc, elem, prop, false, element, []);
} else {
newDesc[previousProp = prop] = elem;
}
}
}
$$[property] = [globalObject, newDesc];
classes.push(property);
}
}
}
function addStubs(descriptor, array, name, isStatic, originalDescriptor, functions) {
var f, funcs = [originalDescriptor[name] = descriptor[name] = f = array[0]];
f.$stubName = name;
functions.push(name);
for (var index = 0; index < array.length; index += 2) {
f = array[index + 1];
if (typeof f != "function") break;
f.$stubName = array[index + 2];
funcs.push(f);
if (f.$stubName) {
originalDescriptor[f.$stubName] = descriptor[f.$stubName] = f;
functions.push(f.$stubName);
}
}
for (var i = 0; i < funcs.length; index++, i++) {
funcs[i].$callName = array[index + 1];
}
var getterStubName = array[++index];
array = array.slice(++index);
var requiredParameterInfo = array[0];
var requiredParameterCount = requiredParameterInfo >> 1;
var isAccessor = (requiredParameterInfo & 1) === 1;
var isSetter = requiredParameterInfo === 3;
var isGetter = requiredParameterInfo === 1;
var optionalParameterInfo = array[1];
var optionalParameterCount = optionalParameterInfo >> 1;
var optionalParametersAreNamed = (optionalParameterInfo & 1) === 1;
var isIntercepted = requiredParameterCount + optionalParameterCount != funcs[0].length;
var functionTypeIndex = array[2];
var unmangledNameIndex = 2 * optionalParameterCount + requiredParameterCount + 3;
var isReflectable = array.length > unmangledNameIndex;
if (getterStubName) {
f = tearOff(funcs, array, isStatic, name, isIntercepted);
f.getterStub = true;
if (isStatic) init.globalFunctions[name] = f;
originalDescriptor[getterStubName] = descriptor[getterStubName] = f;
funcs.push(f);
if (getterStubName) functions.push(getterStubName);
f.$stubName = getterStubName;
f.$callName = null;
if (isIntercepted) init.interceptedNames[getterStubName] = true;
}
if (isReflectable) {
for (var i = 0; i < funcs.length; i++) {
funcs[i].$reflectable = 1;
funcs[i].$reflectionInfo = array;
}
var mangledNames = isStatic ? init.mangledGlobalNames : init.mangledNames;
var unmangledName = array[unmangledNameIndex];
var reflectionName = unmangledName;
if (getterStubName) mangledNames[getterStubName] = reflectionName;
if (isSetter) {
reflectionName += "=";
} else if (!isGetter) {
reflectionName += ":" + requiredParameterCount + ":" + optionalParameterCount;
}
mangledNames[name] = reflectionName;
funcs[0].$reflectionName = reflectionName;
funcs[0].$metadataIndex = unmangledNameIndex + 1;
if (optionalParameterCount) descriptor[unmangledName + "*"] = funcs[0];
}
}
function tearOffGetterNoCsp(funcs, reflectionInfo, name, isIntercepted) {
return isIntercepted
? new Function("funcs", "reflectionInfo", "name", "H", "c",
"return function tearOff_" + name + (functionCounter++)+ "(x) {" +
"if (c === null) c = H.closureFromTearOff(" +
"this, funcs, reflectionInfo, false, [x], name);" +
"return new c(this, funcs[0], x, name);" +
"}")(funcs, reflectionInfo, name, H, null)
: new Function("funcs", "reflectionInfo", "name", "H", "c",
"return function tearOff_" + name + (functionCounter++)+ "() {" +
"if (c === null) c = H.closureFromTearOff(" +
"this, funcs, reflectionInfo, false, [], name);" +
"return new c(this, funcs[0], null, name);" +
"}")(funcs, reflectionInfo, name, H, null)
}
function tearOffGetterCsp(funcs, reflectionInfo, name, isIntercepted) {
var cache = null;
return isIntercepted
? function(x) {
if (cache === null) cache = H.closureFromTearOff(this, funcs, reflectionInfo, false, [x], name);
return new cache(this, funcs[0], x, name)
}
: function() {
if (cache === null) cache = H.closureFromTearOff(this, funcs, reflectionInfo, false, [], name);
return new cache(this, funcs[0], null, name)
}
}
function tearOff(funcs, reflectionInfo, isStatic, name, isIntercepted) {
var cache;
return isStatic
? function() {
if (cache === void 0) cache = H.closureFromTearOff(this, funcs, reflectionInfo, true, [], name).prototype;
return cache;
}
: tearOffGetter(funcs, reflectionInfo, name, isIntercepted);
}
var functionCounter = 0;
var tearOffGetter = (typeof dart_precompiled == "function")
? tearOffGetterCsp : tearOffGetterNoCsp;
if (!init.libraries) init.libraries = [];
if (!init.mangledNames) init.mangledNames = map();
if (!init.mangledGlobalNames) init.mangledGlobalNames = map();
if (!init.statics) init.statics = map();
if (!init.typeInformation) init.typeInformation = map();
if (!init.globalFunctions) init.globalFunctions = map();
if (!init.interceptedNames) init.interceptedNames = map();
var libraries = init.libraries;
var mangledNames = init.mangledNames;
var mangledGlobalNames = init.mangledGlobalNames;
var hasOwnProperty = Object.prototype.hasOwnProperty;
var length = reflectionData.length;
for (var i = 0; i < length; i++) {
var data = reflectionData[i];
var name = data[0];
var uri = data[1];
var metadata = data[2];
var globalObject = data[3];
var descriptor = data[4];
var isRoot = !!data[5];
var fields = descriptor && descriptor["^"];
var classes = [];
var functions = [];
processStatics(descriptor);
libraries.push([name, uri, classes, functions, metadata, fields, isRoot,
globalObject]);
}
})
([
["Repo", "repo.dart", , F, {
"^": "",
main: function() {
return C.Type_Jeh;
}
},
1],
["_js_helper", "dart:_js_helper", , H, {
"^": "",
createRuntimeType: function($name) {
return new H.TypeImpl($name, null);
},
TypeImpl: {
"^": "Object;_typeName,_unmangledName"
}
}],
["dart.core", "dart:core", , P, {
"^": "",
Null: {
"^": "Object;"
},
Object: {
"^": ";"
}
}],
]);
Isolate.$finishClasses($$, $, null);
$$ = null;
// Runtime type support
// getInterceptor methods
C.Type_Jeh = H.createRuntimeType('Repo');
$.libraries_to_load = {};
$.Closure_functionCounter = 0;
$.BoundClosure_selfFieldNameCache = null;
$.BoundClosure_receiverFieldNameCache = null;
init.functionAliases = {};
;
init.metadata = [];
$ = null;
Isolate = Isolate.$finishIsolateConstructor(Isolate);
$ = new Isolate();
function convertToFastObject(properties) {
function MyClass() {};
MyClass.prototype = properties;
new MyClass();
return properties;
}
A = convertToFastObject(A);
B = convertToFastObject(B);
C = convertToFastObject(C);
D = convertToFastObject(D);
E = convertToFastObject(E);
F = convertToFastObject(F);
G = convertToFastObject(G);
H = convertToFastObject(H);
J = convertToFastObject(J);
K = convertToFastObject(K);
L = convertToFastObject(L);
M = convertToFastObject(M);
N = convertToFastObject(N);
O = convertToFastObject(O);
P = convertToFastObject(P);
Q = convertToFastObject(Q);
R = convertToFastObject(R);
S = convertToFastObject(S);
T = convertToFastObject(T);
U = convertToFastObject(U);
V = convertToFastObject(V);
W = convertToFastObject(W);
X = convertToFastObject(X);
Y = convertToFastObject(Y);
Z = convertToFastObject(Z);
// BEGIN invoke [main].
;(function (callback) {
if (typeof document === "undefined") {
callback(null);
return;
}
if (document.currentScript) {
callback(document.currentScript);
return;
}
var scripts = document.scripts;
function onLoad(event) {
for (var i = 0; i < scripts.length; ++i) {
scripts[i].removeEventListener("load", onLoad, false);
}
callback(event.target);
}
for (var i = 0; i < scripts.length; ++i) {
scripts[i].addEventListener("load", onLoad, false);
}
})(function(currentScript) {
init.currentScript = currentScript;
if (typeof dartMainRunner === "function") {
dartMainRunner(F.main, []);
} else {
F.main([]);
}
});
// END invoke [main].
function init() {
Isolate.$isolateProperties = {};
function generateAccessor(fieldDescriptor, accessors, cls) {
var fieldInformation = fieldDescriptor.split("-");
var field = fieldInformation[0];
var len = field.length;
var code = field.charCodeAt(len - 1);
var reflectable;
if (fieldInformation.length > 1)
reflectable = true;
else
reflectable = false;
code = code >= 60 && code <= 64 ? code - 59 : code >= 123 && code <= 126 ? code - 117 : code >= 37 && code <= 43 ? code - 27 : 0;
if (code) {
var getterCode = code & 3;
var setterCode = code >> 2;
var accessorName = field = field.substring(0, len - 1);
var divider = field.indexOf(":");
if (divider > 0) {
accessorName = field.substring(0, divider);
field = field.substring(divider + 1);
}
if (getterCode) {
var args = getterCode & 2 ? "receiver" : "";
var receiver = getterCode & 1 ? "this" : "receiver";
var body = "return " + receiver + "." + field;
var property = cls + ".prototype.get$" + accessorName + "=";
var fn = "function(" + args + "){" + body + "}";
if (reflectable)
accessors.push(property + "$reflectable(" + fn + ");\n");
else
accessors.push(property + fn + ";\n");
}
if (setterCode) {
var args = setterCode & 2 ? "receiver, value" : "value";
var receiver = setterCode & 1 ? "this" : "receiver";
var body = receiver + "." + field + " = value";
var property = cls + ".prototype.set$" + accessorName + "=";
var fn = "function(" + args + "){" + body + "}";
if (reflectable)
accessors.push(property + "$reflectable(" + fn + ");\n");
else
accessors.push(property + fn + ";\n");
}
}
return field;
}
Isolate.$isolateProperties.$generateAccessor = generateAccessor;
function defineClass(name, cls, fields) {
var accessors = [];
var str = "function " + cls + "(";
var body = "";
for (var i = 0; i < fields.length; i++) {
if (i != 0)
str += ", ";
var field = generateAccessor(fields[i], accessors, cls);
var parameter = "parameter_" + field;
str += parameter;
body += "this." + field + " = " + parameter + ";\n";
}
str += ") {\n" + body + "}\n";
str += cls + ".builtin$cls=\"" + name + "\";\n";
str += "$desc=$collectedClasses." + cls + ";\n";
str += "if($desc instanceof Array) $desc = $desc[1];\n";
str += cls + ".prototype = $desc;\n";
if (typeof defineClass.name != "string") {
str += cls + ".name=\"" + cls + "\";\n";
}
str += accessors.join("");
return str;
}
var inheritFrom = function() {
function tmp() {
}
var hasOwnProperty = Object.prototype.hasOwnProperty;
return function(constructor, superConstructor) {
tmp.prototype = superConstructor.prototype;
var object = new tmp();
var properties = constructor.prototype;
for (var member in properties)
if (hasOwnProperty.call(properties, member))
object[member] = properties[member];
object.constructor = constructor;
constructor.prototype = object;
return object;
};
}();
Isolate.$finishClasses = function(collectedClasses, isolateProperties, existingIsolateProperties) {
var pendingClasses = {};
if (!init.allClasses)
init.allClasses = {};
var allClasses = init.allClasses;
var hasOwnProperty = Object.prototype.hasOwnProperty;
if (typeof dart_precompiled == "function") {
var constructors = dart_precompiled(collectedClasses);
} else {
var combinedConstructorFunction = "function $reflectable(fn){fn.$reflectable=1;return fn};\n" + "var $desc;\n";
var constructorsList = [];
}
for (var cls in collectedClasses) {
if (hasOwnProperty.call(collectedClasses, cls)) {
var desc = collectedClasses[cls];
if (desc instanceof Array)
desc = desc[1];
var classData = desc["^"], supr, name = cls, fields = classData;
if (typeof classData == "string") {
var split = classData.split("/");
if (split.length == 2) {
name = split[0];
fields = split[1];
}
}
var s = fields.split(";");
fields = s[1] == "" ? [] : s[1].split(",");
supr = s[0];
split = supr.split(":");
if (split.length == 2) {
supr = split[0];
var functionSignature = split[1];
if (functionSignature)
desc.$signature = function(s) {
return function() {
return init.metadata[s];
};
}(functionSignature);
}
if (typeof dart_precompiled != "function") {
combinedConstructorFunction += defineClass(name, cls, fields);
constructorsList.push(cls);
}
if (supr)
pendingClasses[cls] = supr;
}
}
if (typeof dart_precompiled != "function") {
combinedConstructorFunction += "return [\n " + constructorsList.join(",\n ") + "\n]";
var constructors = new Function("$collectedClasses", combinedConstructorFunction)(collectedClasses);
combinedConstructorFunction = null;
}
for (var i = 0; i < constructors.length; i++) {
var constructor = constructors[i];
var cls = constructor.name;
var desc = collectedClasses[cls];
var globalObject = isolateProperties;
if (desc instanceof Array) {
globalObject = desc[0] || isolateProperties;
desc = desc[1];
}
allClasses[cls] = constructor;
globalObject[cls] = constructor;
}
constructors = null;
var finishedClasses = {};
init.interceptorsByTag = Object.create(null);
init.leafTags = {};
function finishClass(cls) {
var hasOwnProperty = Object.prototype.hasOwnProperty;
if (hasOwnProperty.call(finishedClasses, cls))
return;
finishedClasses[cls] = true;
var superclass = pendingClasses[cls];
if (!superclass || typeof superclass != "string")
return;
finishClass(superclass);
var constructor = allClasses[cls];
var superConstructor = allClasses[superclass];
if (!superConstructor)
superConstructor = existingIsolateProperties[superclass];
var prototype = inheritFrom(constructor, superConstructor);
}
for (var cls in pendingClasses)
finishClass(cls);
};
Isolate.$lazy = function(prototype, staticName, fieldName, getterName, lazyValue) {
var sentinelUndefined = {};
var sentinelInProgress = {};
prototype[fieldName] = sentinelUndefined;
prototype[getterName] = function() {
var result = $[fieldName];
try {
if (result === sentinelUndefined) {
$[fieldName] = sentinelInProgress;
try {
result = $[fieldName] = lazyValue();
} finally {
if (result === sentinelUndefined) {
if ($[fieldName] === sentinelInProgress) {
$[fieldName] = null;
}
}
}
} else {
if (result === sentinelInProgress)
H.throwCyclicInit(staticName);
}
return result;
} finally {
$[getterName] = function() {
return this[fieldName];
};
}
};
};
Isolate.$finishIsolateConstructor = function(oldIsolate) {
var isolateProperties = oldIsolate.$isolateProperties;
function Isolate() {
var hasOwnProperty = Object.prototype.hasOwnProperty;
for (var staticName in isolateProperties)
if (hasOwnProperty.call(isolateProperties, staticName))
this[staticName] = isolateProperties[staticName];
function ForceEfficientMap() {
}
ForceEfficientMap.prototype = this;
new ForceEfficientMap();
}
Isolate.prototype = oldIsolate.prototype;
Isolate.prototype.constructor = Isolate;
Isolate.$isolateProperties = isolateProperties;
Isolate.$finishClasses = oldIsolate.$finishClasses;
return Isolate;
};
}
})()
//# sourceMappingURL=out.js.map
//@ sourceMappingURL=out.js.map
就是这样，我抛弃了Dart，因为我不知道如何处理生成的JS文件，害怕可能需要大量的时间来保持生成的库接口干净，类似于我使用的JavaScript。
And that's it, I've thrown away Dart because I didn't knew what to do with generated JS file, also I was frightened of potentially high amount of time required for keeping the resulting library interface clean and similar to one I'm using with JavaScript.
- 如何公开在Dart中创建的类定义，然后在JavaScript中使用它们？
- 值得去Dart，几乎所有潜在的图书馆用户都将使用JS版本？ （由于社区大小不同，使用dart已经不适合我，这意味着更少的人会很容易为我的图书馆贡献）
- 在你看来，我应该怎么办？
推荐答案
即使Dart支持这种用例，
Even though Dart supports this use case, if you target JavaScript developers I would stick with JavaScript.
@AlexandreArdhuin在回答将Dart函数公开给javascript时显示<
根据 dart-js-interop 是很多例子，说明如何在Dart和JavaScript之间执行函数调用和传递数据。
@AlexandreArdhuin shows in his answer to Expose Dart functions to javascript how you can make a Dart function available to JavaScript.
Under the dart-js-interop are many examples how to do function calls and pass data between Dart and JavaScript.
这篇关于使用dart创建一个javascript库的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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