Curious - why create the concat call inside the loop of template spans instead of outside the loop?

In other words, why does a${x}b${y}c emit "a".concat(x, "b").concat(y, "c") instead of emitting "a".concat(x, "b", y, "c")?

@leebyron i believe the observable order of exceptions from ToString calls may require the chained calls; babel had the same change (please double check me)

Aha, yes thank you for this.

There's a test included in this change that would break based on that idea

class C {
    counter: number;
    constructor() {
        this.counter = 0;
    }
    get foo() {
        this.counter++;
        return {
            toString: () => this.counter++,
        };
    }
}
const c = new C;
export const output = \`\${c.foo} \${c.foo}\`;

"".concat(c.foo).concat(c.foo) would run: get foo(), toString(), get foo(), toString()

and

"".concat(c.foo, c.foo) would run: get foo(), get foo(), toString(), toString()

The first one is what you'd expect to see from a template interpolation