Javascript 如何获取字符串除最后两位数字以外的所有字符的 substr？（例如：031p2 >> 得到 031）
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How to get substr of the string's all characters except for the last two digits? (ex: 031p2 >> get 031)
提问by Logan
id = '01d0';
document.write('<br/>'+id.substr(0,-2));
How can I get the 01without the last two chars? The trick is that if i do it like (0,2)it does get the first 2 numbers but this id will also be a three digit number... so I just need to get rid of the last two digits. This works with substrin PHP, how come (0,-2)doesn't work with javascript? More importantly how can i make this work?
我怎样才能得到01没有最后两个字符的？诀窍是，如果我这样做，(0,2)它确实会得到前 2 个数字，但这个 id 也将是一个三位数……所以我只需要去掉最后两个数字。这substr在 PHP 中有效，为什么(0,-2)在 javascript 中不起作用？更重要的是我怎样才能做到这一点？
回答by James Allardice
Try id.substring(0, id.length - 2);
尝试 id.substring(0, id.length - 2);
回答by Cyril N.
var str = "031p2";
str.substring(0, str.length-2);
回答by Tom Wadley
Something like:
就像是：
id.substr(0, id.length - 2)
The first parameter of substris the starting index. The second parameter is how many characters to take.
substr的第一个参数是起始索引。第二个参数是要取多少个字符。
