表单验证正则表达式和DOM：什么是在表单验证中实现正则表达式的最佳方法

Question

Form validation regex and DOM: What would be the best way to implement regex in a form validation?

Im currently doing this, but when I validate it's not matching the values:

if(this.value.length > 0 && this.value === /^[a-zA-Z]+$/ );

Thank You in advance!

Answer 1

you need to use the test() method.

var patt = /^[a-zA-Z]+$/; //define your RegEx

    if(this.value.length > 0 && patt.test(this.value)){ //check if this.value is longer than one character AND matches your RegEx
           //do something
     };

See http://www.w3schools.com/jsref/jsref_regexp_test.asp

Answer 2

Why you code does not mathing any values? Because you used typewise equality test === . In dynamic types of JavaScript world it states for: test types of those values if they are the same and then test values if they are equal. So when you were trying to test in that way values of some textboxes, which are strings

typeof('a')

this code will yield "string" because of 'a' is indeed a string. But:

typeof(/^[a-zA-Z]+$/)

this will yield "object". As you see typewise equality test will always return false when you are trying compare string to object.

That is for testing equality of objects and its values. For regex see 'bam' answer.