Round For JavaScript

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Round For JavaScript

這篇介紹在JavaScript對數字做四捨五入到小數第二位需要注意事項。

錯誤case

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Math.round(127.825 * 100)/100 ----> 127.83 (O)
Math.round(128.825 * 100)/100 ----> 128.82 (X)

解決方法

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const roundFormat = function (value, arg) {
	var fixed = arg || 0;
	isNaN(parseFloat(value)) ? value = 0 : value = parseFloat(value);
	if (fixed > 0) {
		var size = Math.pow(10, fixed);
		value = Math.round(value + "e" + fixed) / size;
	}
};

roundFormat(127.825, 2);  ------> 127.83 (O)
roundFormat(128.825, 2);  ------> 128.83 (O)