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[英]How do I know, via key event code, if the character just entered in a <textarea> is lower or upper case?
[英]How to know if a regex failed on the lower or upper bound of a character size limit set with a quantifier
量词可用于正则表达式中以匹配大小限制内的字符串:
"54 343 2356 2".match(/\d{3,4}/) // 343, 2356
如果我想针对带有量词的正则表达式测试字符串,我怎么知道测试是否在字符大小限制的下限或上限上失败?
/\d{3,4}/.test("54525")
如果测试在字符大小限制的下限或上限上失败?
为此,您不需要正则表达式,而是执行if-else 条件,因此计算该数字中的位数:
let x = "54525"; if (x.length < 3) { console.log(x + ' has less digits than 3'); } else if (x.length > 4) { console.log(x + ' has more digits than 4'); } else { console.log(x + ' has exactly number of digits between 3 or 4'); }
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