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Prototype assignment should take the type of the initializer and not require a literal #39166
Description
This is a feature request based on actual VS customer code.
TypeScript Version: 3.9.2
Search Terms: ES5 class javascript prototype assignment constructor function
Expected behavior: In the example below, the prototype for test.class should include properties from testPrototype.
Actual behavior: Per Nathan Shively-Sanders (@sandersn) this pattern is recognized in the binder and only uses syntactic information, therefore does not use the type information from testPrototype .
Related Issues: #39167 from same user code. Also #33454 maybe?
Code
var test = {};
test.testPrototype = {
add: function (i) {
}
}
test.class = function (name) {
function getName() {
return name;
}
this.name = getName();
}
test.class.prototype = test.testPrototype;
var t = new test.class("test");
t.name
t.add // EXPECTED: Binds to `add` from the prototype, ACTUAL: doesn't
//
// Same pattern works when a literal is assigned to the prototype:
//
var test2 = {};
test2.class = function (name) {
function getName() {
return name;
}
this.name = getName();
}
// replaced `test.testPrototype` with a literal
test2.class.prototype = {
add: function (i) {
}
};
var t2 = new test2.class("test");
t2.name
t2.add // ACTUAL: `add` bound correctlyCompiler Options
{
"compilerOptions": {
"noImplicitAny": true,
"strictFunctionTypes": true,
"strictPropertyInitialization": true,
"strictBindCallApply": true,
"noImplicitThis": true,
"noImplicitReturns": true,
"alwaysStrict": true,
"esModuleInterop": true,
"checkJs": true,
"allowJs": true,
"declaration": true,
"experimentalDecorators": true,
"emitDecoratorMetadata": true,
"moduleResolution": 2,
"target": "ES2017",
"jsx": "React",
"module": "ESNext"
}
}Playground Link: Provided
Activity