33 lines
1.1 KiB
JavaScript
33 lines
1.1 KiB
JavaScript
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/**
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* Calculates a number's precision based on the number of trailing
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* zeros if the number does not have a decimal indicated by a negative
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* precision. Otherwise, it calculates the number of digits after
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* the decimal point indicated by a positive precision.
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* @param value - the value to determine the precision of
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*/ export function calculatePrecision(value) {
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/**
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* Group 1:
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* [1-9]([0]+$) matches trailing zeros
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* Group 2:
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* \.([0-9]*) matches all digits after a decimal point.
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*/ const groups = /[1-9]([0]+$)|\.([0-9]*)/.exec(String(value));
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if (!groups) {
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return 0;
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}
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if (groups[1]) {
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return -groups[1].length;
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}
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if (groups[2]) {
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return groups[2].length;
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}
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return 0;
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}
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/**
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* Rounds a number to a certain level of precision. Accepts negative precision.
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* @param value - The value that is being rounded.
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* @param precision - The number of decimal places to round the number to
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*/ export function precisionRound(value, precision, base = 10) {
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const exp = Math.pow(base, precision);
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return Math.round(value * exp) / exp;
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}
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