55 lines
1.9 KiB
JavaScript
55 lines
1.9 KiB
JavaScript
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function round (value, precision, mode) {
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// http://kevin.vanzonneveld.net
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// + original by: Philip Peterson
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// + revised by: Onno Marsman
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// + input by: Greenseed
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// + revised by: T.Wild
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// + input by: meo
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// + input by: William
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// + bugfixed by: Brett Zamir (http://brett-zamir.me)
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// + input by: Josep Sanz (http://www.ws3.es/)
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// + revised by: Rafał Kukawski (http://blog.kukawski.pl/)
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// % note 1: Great work. Ideas for improvement:
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// % note 1: - code more compliant with developer guidelines
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// % note 1: - for implementing PHP constant arguments look at
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// % note 1: the pathinfo() function, it offers the greatest
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// % note 1: flexibility & compatibility possible
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// * example 1: round(1241757, -3);
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// * returns 1: 1242000
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// * example 2: round(3.6);
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// * returns 2: 4
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// * example 3: round(2.835, 2);
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// * returns 3: 2.84
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// * example 4: round(1.1749999999999, 2);
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// * returns 4: 1.17
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// * example 5: round(58551.799999999996, 2);
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// * returns 5: 58551.8
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var m, f, isHalf, sgn; // helper variables
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precision |= 0; // making sure precision is integer
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m = Math.pow(10, precision);
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value *= m;
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sgn = (value > 0) | -(value < 0); // sign of the number
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isHalf = value % 1 === 0.5 * sgn;
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f = Math.floor(value);
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if (isHalf) {
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switch (mode) {
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case '2':
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case 'PHP_ROUND_HALF_DOWN':
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value = f + (sgn < 0); // rounds .5 toward zero
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break;
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case '3':
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case 'PHP_ROUND_HALF_EVEN':
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value = f + (f % 2 * sgn); // rouds .5 towards the next even integer
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break;
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case '4':
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case 'PHP_ROUND_HALF_ODD':
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value = f + !(f % 2); // rounds .5 towards the next odd integer
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break;
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default:
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value = f + (sgn > 0); // rounds .5 away from zero
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}
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}
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return (isHalf ? value : Math.round(value)) / m;
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}
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