35 lines
1.3 KiB
JavaScript
35 lines
1.3 KiB
JavaScript
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function getROA() {
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// Get values from page
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var startSize = document.getElementById("startSize").value;
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var finalSize = document.getElementById("finalSize").value;
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// If mm is selected we convert it to inches
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if (document.getElementById("metric").checked == true) {
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startSize = Math.round((startSize * 1000) / 25.4);
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}
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// Format our numbers to prevent maximum user stupidity
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if (startSize < 1.0 && startSize > 0) { // If we have a 'proper' number i.e. ".130"
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startSize = startSize * 1000;
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} else { // re-format the number if it's 'wrong' i.e. "130"
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startSize = Number(startSize);
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}
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if (finalSize < 1.0 && finalSize > 0) { // If we have a 'proper' number i.e. ".130"
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finalSize = finalSize * 1000;
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} else { // re-format the number if it's 'wrong' i.e. "130"
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finalSize = Number(finalSize);
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}
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// Get area from diameter
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var startArea = Math.PI * ((startSize / 2) * (startSize / 2));
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var finalArea = Math.PI * ((finalSize / 2) * (finalSize / 2));
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// Calculate reduction
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var reduction = ((startArea - finalArea) / startArea) * 100;
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// Round to two decimals
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reduction = Math.round(reduction * 100) / 100;
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// Display
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document.getElementById("result").innerHTML = reduction + "%";
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}
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