Using if conditional ti turn buzzer on when lght is above a certain point

Hi. I want to turn on my buzzer as soon as the light intensity goes above 100. I tried the follwoing code but that only plots the graph and the buzzer does not work.
Here is the code:
setChartLibrary(‘google-chart’);
setChartType(‘areaGraph’);
plotChart(‘time_stamp’, ‘ldr’);
dataDownload(false);
if ( analogRead(A0) > 100){
digitalWrite(0, ‘HIGH’); }

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