Javascript正则表达式检查重复单词模式

Question

How to parse string no check is it in valid pattern?

1. I need to find are there words AND or OR
2. I need to check are they surrounded by another words, but not AND or OR

If it is valid i will build query.

Examples:

a and b or c -> valid
a and or b   -> invalid
a or and b   -> invalid
a or b       -> valid
a and b or   -> invalid
and b or c   -> invalid

Answer 1

Would you be fine with a non-regex solution?

Try this

 function isValid( str ) { return str.split(/\\s*and\\s*|\\s*or\\s*/g).filter( function(item){ return item.length == 0 ; }).length == 0; } console.log( isValid( "a and b or c" ) ); console.log( isValid( "a and or b" ) ); console.log( isValid( "a or and b" ) ); console.log( isValid( "a or b" ) ); console.log( isValid( "a and b or" ) ); console.log( isValid( "and b or c" ) ); console.log( isValid( "a and bc" ) ); 

isValid first split the string based on and and or , then checks if the returned array has an empty element or not.

Answer 2

Try this regex:

^(?=.*(?:and|or).*$)(?!(?:"\s*")*\s*(?:and|or))(?!.*(?:and|or)\s*(?:"\s*")*$)(?!.*and\s+or)(?!.*or\s+and).*$

Demo

Explanation:

• ^ - Start of the String
• (?!\\s*(?:and|or)) - Negative lookahead - makes sure that and or or are not present at the beginning of the string preceded by 0+ spaces
• (?!.*(?:and|or)\\s*$) - Negative lookahead - makes sure that and or or are not present at the end of the string followed by 0+ spaces
• (?!.*and\\s+or) - makes sure or does not follow immediately after and and 1+ spaces
• (?!.*or\\s+and) - makes sure 'and' does not follow immediately after or and 1+ spaces
• .+ - match anything but new line characters
• $ - End of String

Update: