This paper introduces programmable text rendering that enables temporal typography in web browsers. Typing is seen not only as a dynamic but interactive process facilitating both scripted and live musical expression in various contexts such as audio-visual performance using keyboards and live coding visualization. With the programmable text animation , we turn plain text into a highly audiovisual medium and a musical interface which is visually expressive. We describe a concrete technical realization of the concept using Web Audio API, WebGL and GLSL shaders. We further show a number of examples that illustrate instances of the concept in various scenarios ranging from simple textual visualization to live coding environments. Lastly, we present an audiovisual music piece that involves live writing augmented by the visualization technique.