Typescript Prototype issue

Question

I am having an issue creating a prototype in TypeScript, when I use the method I get "TypeError: t.stringTesting is not a function"

below is the code.

extensions.ts

interface String {
    stringTesting() : string;
}

String.prototype.stringTesting = function (): string {
    return "testing"
}

in my Angular2 component I am using

var t: string = "";
t = t.stringTesting();
alert(t);

Your code is working fine. You probably don't load this extensions.js at runtime — Nitzan Tomer
– Nitzan Tomer, Commented Aug 15, 2016 at 13:14

basarat · Accepted Answer · 2016-08-15 23:37:38Z

1

t.stringTesting is not a function"

You need to make sure the extensions.js runs before any code that uses it.

answered Aug 15, 2016 at 23:37

basarat

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