標籤：button var length win style ack type alert onclick
這裡主要考慮的是日文，日文中包含了半形和全形文字，半形算1，全形算2.
<html><head><script language="javascript">function alertLength(){ var name = document.main.name.value; window.alert("入力文字：【" + name + "】"); var length = countLength(name); window.alert("バイト數：" + length);}function countLength(str) { var r = 0; for (var i = 0; i < str.length; i++) { var c = str.charCodeAt(i); // Shift_JIS: 0x0 ～ 0x80, 0xa0 , 0xa1 ～ 0xdf , 0xfd ～ 0xff // Unicode : 0x0 ～ 0x80, 0xf8f0, 0xff61 ～ 0xff9f, 0xf8f1 ～ 0xf8f3 if ( (c >= 0x0 && c < 0x81) || (c == 0xf8f0) || (c >= 0xff61 && c < 0xffa0) || (c >= 0xf8f1 && c < 0xf8f4)) { r += 1; } else { r += 2; } } return r; } </script></head><body><form name="main"><input type="text" name="name"><input type="button" onClick="alertLength()"></form></body></html>
js統計輸入文字的位元組數(byte)
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