javascript中只能访问小数和数字的正则表达式

Question

I want to make regular expression which supports all below numbers,

• Max length of the number : 7
• Max length of decimal places: 2

Example:

• Valid : 500, 1234567, 350.75, 7500.05, 4500.3
• Not valid : 100.123, 12345678, 45000.25

I tried with

<input type='number' pattern="/^\\d{1,7}(\\.\\d{1,2})?$/"/>

but its not satisfying the max length value.

Kindly help in this issue.

Answer 1

Check length via lookahead.

               ↓               ↓       CHANGE THESE PARAMETERS
/^(?=(.[.]?){1,7}$)\d*([.]\d{1,2})?$/
  |---------------|                    LOOK-AHEAD TO CHECK LENGTH
                   |-|                 INTEGER PORTION OF NUMBER
                      |-----------|    OPTIONAL DECIMAL PORTION OF NUMBER

This is more easily scalable to variations of the problem such as "up to seven total digits with up to four decimal places" than other solutions are. Just replace the two characters pointed to by "CHANGE THESE PARAMETERS".

Answer 2

Pretty sure this will do it for ya:

^(\d{1,5}\.\d{2}|\d{1,6}\.\d|\d{1,7})$

Anything that is 5.2 or 6.1 or 7 digits (max number of characters)

Answer 3

Here's a jsbin for the pattern.

var re = /^(\d{1,7}|\d{1,6}\.\d|\d{1,5}\.\d{1,2})$/;

function validate(str) {
  return (str).match(re) !== null;
}

function assert(value, expected) {
  return value === expected;
}

console.log(
  assert(validate("1234567"), true)
);

console.log(
  assert(validate("123456.7"), true)
);

console.log(
  assert(validate("12345.67"), true)
);

console.log(
  assert(validate("1234.567"), false)
);

console.log(
  assert(validate("12345.678"), false)
);

console.log(
  assert(validate("123456.78"), false)
);

console.log(
  assert(validate("1234567.8"), false)
);

console.log(
  assert(validate("12345678"), false)
);