payments

2 posts

Jul 28, 2026

The QR Code That Didn't Pay — String.fromCharCode, Control Codepoints, and an Invisible Pix

I added Pix to my portfolio with BR Code generation. Only the QR Code didn't work in any banking app. The culprit: String.fromCharCode generating control characters instead of decimal digits in EMV 2022 length fields.

portfolio javascript debugging

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Portfólio

Jul 28, 2026

O Pix que não Pixava — String.fromCharCode, codepoints de controle e um BR Code invisível

Implementei Pix no portfólio com pagamento via BR Code. Só que o QR Code não funcionava em nenhum app de banco. O culpado: String.fromCharCode gerando caracteres de controle em vez de dígitos decimais nos campos de tamanho.

portfolio javascript debugging

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The QR Code That Didn't Pay — String.fromCharCode, Control Codepoints, and an Invisible Pix

O Pix que não Pixava — String.fromCharCode, codepoints de controle e um BR Code invisível