61 lines
1.6 KiB
JavaScript
61 lines
1.6 KiB
JavaScript
/* @providesModule This */
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function F() { this.x = 0; }
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F.prototype.m = function() { this.y = 0; }
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function foo(p:string) { }
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var o1 = new F(); // sets o1.x to 0
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o1.x = "";
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foo(o1.x); // ok by definite assignment
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var o2 = new F();
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o1.y = 0;
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o2.y = "";
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foo(o2.y); // setting o1.y to 0 has no effect on o2.y
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var o3 = new F();
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o3.m(); // sets o3.y to 0
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o3.y = "";
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foo(o3.y); // ok by definite assignment
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foo(o2.y); // setting o3.y to 0 has no effect on o2.y
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/*
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* this bindings:
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*/
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/* standard functions may rebind this */
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function f1() : number {
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return this.x
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}
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var f1_1 = f1.bind({x: 0})(); // ok
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var f1_2 : string = f1.bind({x: 0})(); // error, number -> string
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var f1_3 = f1.bind({x: ""})(); // error, string -> number
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// TODO make this error blame the call site, rather than the function body
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var f1_4 = f1(); // error, (global object).x
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/* arrow functions bind this at point of definition */
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/* top level arrow functions bind this to global object */
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var a1 = () => {
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return this.x
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}
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var ax = a1(); // error, (this:mixed).x
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/* nested arrows bind enclosing this (which may itself rebind) */
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function f2() : number {
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var a2 = () => { return this.x };
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return a2()
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}
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var f2_1 = f2.bind({x: 0})(); // ok
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var f2_2 : string = f2.bind({x: 0})(); // error, number -> string
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var f2_3 = f2.bind({x: ""})(); // error, string -> number
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// TODO make this error blame the call site, rather than the function body
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var f2_4 = f2(); // error, (global object).x
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(this: void);
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module.exports = true;
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