如何使用jquery从字符串中获取前4个字母 [英] How get first 4 letters from string by using jquery

问题描述

我想从字符串中获得前4位数字

但是它显示为null



我怎么会在这里弄错



我的尝试：

I am trying to get first 4 digit from string
but its show null

how i mistaken here

What I have tried:

alert("Result " + n_result);
      //n_result val 1500.02154
      lbtot1 = (n_result / 11)
      //lbtot1=136.36559454
      alert(lbtot1);
      var str1 = (n_result / 11);
      // str1 val = 136.36559454
      alert(str1 + " str1");


      var resu1 = str1.substring(0, 4);
      alert(resu1);
     // here he did not alert any value
     //did't show value
    // here i want to check is 4th digit/letters/chr  (136.) chr is "." or number

推荐答案

Quote：

这里我要检查的是第4位/字母/ chr（136.）chr是。或数字

here i want to check is 4th digit/letters/chr (136.) chr is "." or number

你不能在 str1 上调用 substring ，因为它是不是一个字符串。但你不需要 - 第四个字符的唯一方式是。如果数字大于或等于 100 ，小于 1000 。如果 n_result 可能为负数，则数字大于 -100 且小于或等于 -10 还将有一个。作为第四个字符。

You can't call substring on str1 because it's not a string. But you don't need to - the only way the 4th character will be "." is if the number is greater than or equal to 100, and less than 1000. If n_result could be negative, then numbers greater than -100 and less than or equal to -10 will also have a "." as the 4th character.

var isFouthCharDot = (lbtot1 >= 100 && lbtot1 < 1000) || (lbtot1 > -100 && lbltot1 <= -10);

作为奖励，这也可以避免使用<$ c $的文化问题c>，作为小数点分隔符。

jquery在这里无关紧要。如果要将数字转换为字符串，请调用str1.toString（）

jquery is irrelevant here. If you want to convert a number into a string, call str1.toString()

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