so I am trying to search a string for a sub string, and apparently, I must use regular expressions with the .search function, this is the code I have
var str = items[i].toLowerCase;
var str2 = document.getElementById("input").value.toLowerCase;
var index = str.search(str2);
Obhiously this doesn't work and I get an error, saying str.search is not a function, how would I go about changing these two strings into regular expressions?
thanks
Use this:
new RegExp("your regex here", "modifiers");
Take a look into:
Using a string variable as regular expression
add braces to your function calls:
var str = items[i].toLowerCase();
var str2 = document.getElementById("input").value.toLowerCase();
var index = str.search(str2);
otherwise type of "str" is a function, not result of function execution
your problem is forgetting a set of brackets () -- and as such str and str2 get assigned a function rather than the result of calling that function! Simply change the code:
var str = items[i].toLowerCase();
var str2 = document.getElementById("input").value.toLowerCase();
var index = str.search(str2);
To use an expression in a RegExp constructor:
var re = new RegExp(str, 'g');
will create a regular expression to match the value of str in a string, so:
var str = 'foo';
var re = new RegExp(str, 'i');
is equivalent to the RegExp literal:
var re = /foo/i;
You can use any expression that evaluates to a valid regular expression, so to match foo at the start of a string:
var re = new RegExp('^' + str, 'i');
The only niggle is that quoted characters must be double quoted, so to match whitespace at the end of a string:
var re = new RegExp('\\s+$');
which is equivalent to:
var re = /\s+$/;
Related
I have a string [TEST][NO CHANGE][TEST][NOW][TEST] in which [TEST] should be replace with 'replaced', and the result should be replaced[NO CHANGE]replaced[NOW]replaced.
I have Tried the following ways, nothing worked.
1. str.replace(/'[TEST]'/g, 'replaced');
2. str.replace(/[TEST]/g, 'replaced');
3. str.replace('/[TEST]/g', 'replaced');
var str = "[TEST][NO CHANGE][TEST][NOW][TEST]";
var resultStr = str.replace(/'[TEST]'/g, 'replaced');
Actual String: [TEST][NO CHANGE][TEST][NOW][TEST]
After Replacing: replaced[NO CHANGE]replaced[NOW]replaced
[] has a special meaning in regex, which means character class, if you want to match [] you need to escape them
var str = "[TEST][NO CHANGE][TEST][NOW][TEST]";
var resultStr = str.replace(/\[TEST\]/g, 'replaced');
console.log(resultStr)
Try to update using Below snippet.
String.prototype.replaceAll = function(search, replacement) {
var target = this;
return target.split(search).join(replacement);
};
var str = "[TEST][NO CHANGE][TEST][NOW][TEST]";
var result = str.replaceAll('\[TEST\]','replaced')
console.log(result);
replaced[NO CHANGE]replaced[NOW]replaced
Src : How to replace all occurrences of a string in JavaScript
Your regular expression in replace is looking for the string '[TEST]' surrounded by those single quotes and is looking to match any of the characters in TEST because you didn't escape the brackets. Try this regular expression instead:
var resultStr = str.replace(/\[TEST\]/g, 'replaced');
I have a string which has some data with a few special characters, Need to remove the data between the desired special char in JavaScript.
The special char would be obtained in a variable.
var desiredChar = "~0~";
And Imagine this to be the Input string:
~0~1|0|20170807|45|111.00|~0~~1~1|0|20170807|50|666.00|~1~~2~1|0|20170807|55|111.00|~2~
So I'm supposed to remove the text in bold.
The desired output is supposed to be-
~1~1|0|20170807|50|666.00|~1~~2~1|0|20170807|55|111.00|~2~
I've tried using "Replace" and "Regex", but as the desired character is being passed in a variable and keeps changing I'm facing difficulties.
You can create your own regex based on whatever the bounding character(s) are that contain the text you want removed, and then replace any text that matches that regex with a blank string "".
The JS below should work for your use case (and it should work for multiple occurrences as well):
var originalText = "~0~1|0|20170807|45|111.00|~0~~1~1|0|20170807|50|666.00|~1~~2~1|0|20170807|55|111.00|~2~";
var desiredChar = "~0~";
var customRegex = new RegExp(desiredChar + ".*?" + desiredChar, "gi");
var processedText = originalText.replace(customRegex, "");
console.log(processedText);
You can build your regex from the constructor with a string input.
var desiredChar = "~0~";
// use the g flag in your regex if you want to remove all substrings between desiredChar
var myRegex = new Regex(desiredChar + ".*" + desiredChar, 'ig');
var testString = "~0~1|0|20170807|45|111.00|~0~~1~1|0|20170807|50|666.00|~1~~2~1|0|20170807|55|111.00|~2~";
testString = testString.replace(myRegex, "");
Given input string you can use .indexOf(), .lastIndexOf() and .slice().
Note, OR character | passed to RegExp constructor should be escaped to avoid RegExp created by passing string interpreting | character as OR | within resulting RegExp passed to .replace().
var desiredChar = "~0~";
var str = "~0~1|0|20170807|45|111.00|~0~~1~1|0|20170807|50|666.00|~1~~2~1|0|20170807|55|111.00|~2~";
var not = str.slice(str.indexOf(desiredChar), str.lastIndexOf(desiredChar) + desiredChar.length);
// escape OR `|`
var res = str.replace(new RegExp(not.replace(/[|]/g, "\\|")), "");
console.log(res)
You can use the RegExp object:
var regexstring = "whatever";
var regexp = new RegExp(regexstring, "gi");
var str = "whateverTest";
var str2 = str.replace(regexp, "other");
document.write(str2);
Then you can construct regexstring in any way you want.
You can read more about it at http://www.regular-expressions.info/javascript.html
This should automatically remove characters NOT on my regex, but if I put in the string asdf sd %$##$, it doesnt remove anything, and if I put in this #sdf%#, it only removes the first character. I'm trying to make it remove any and all instances of those symbols/special characters (anything not on my regex), but its not working all the time. Thanks for any help:
function ohno(){
var pattern = new RegExp("[^a-zA-Z0-9]+");
var str = "#sdf%#"; //"asdf sd %$##$" // Try both
str = str.replace(pattern,' ');
document.getElementById('msg').innerHTML = str;
}
You need the g flag to remove more than one match:
var pattern = new RegExp("[^a-zA-Z0-9]+", "g");
Note that it would be more efficient and readable to use a regex literal instead of the RegExp constructor:
var pattern = /[^a-zA-Z0-9]+/g;
reference
You need to set global using "g", The flag indicates that the regular expression should be tested against all possible matches in a string.
new RegExp("[^a-zA-Z0-9]+", "g")
Reference
var pattern = new RegExp("[^a-zA-Z0-9]+", "g");
var str = "#sdf%#"; //"asdf sd %$##$" // Try both
str = str.replace(pattern,' ');
alert(str)
I am using the function match for a search engine, so whenever a user types a search-string I take that string and use the match function on an array containing country names, but it doesn't seem to work.
For example if I do :
var string = "algeria";
var res = string.match(/alge/g); //alge is what the user would have typed in the search bar
alert(res);
I get a string res = "alge": //thus verifying that alge exists in algeria
But if I do this, it returns null, why? and how can I make it work?
var regex = "/alge/g";
var string = "algeria";
var res = string.match(regex);
alert(res);
To make a regex from a string, you need to create a RegExp object:
var regex = new RegExp("alge", "g");
(Beware that unless your users will be typing actual regular expressions, you'll need to escape any characters that have special meaning within regular expressions - see Is there a RegExp.escape function in Javascript? for ways to do this.)
You don't need quotes around the regex:
var regex = /alge/g;
Remove the quotes around the regex.
var regex = /alge/g;
var string = "algeria";
var res = string.match(regex);
alert(res);
found the answer, the match function takes a regex object so have to do
var regex = new RegExp(string, "g");
var res = text.match(regex);
This works fine
Test string is "page-42440233_45778105"
pattern "(page-\d+_\d+)"
Online tester(http://www.regexr.com/) successfuly finded mathc,but in browser js result is null. Why?
var re = new RegExp("(page-\d+_\d+)", "gim");
var r_array = message.match(re);
console.log(r_array);
I think this would be a better pattern
var re = /^page-\d+_\d+$/i;
It also matches the beginning (^) and end ($) of the string
message.match(re);
//=> ["page-42440233_45778105"]
You need to escape \ if you use string literal:
var message = "page-42440233_45778105";
var re = new RegExp("(page-\\d+_\\d+)", "gim");
var r_array = message.match(re);
console.log(r_array);
// => ["page-42440233_45778105"]
More preferably, use regular expression literal:
var re = /(page-\d+_\d+)/gim;
When you use a string literal, you must escape the \ :
var re = new RegExp("(page-\\d+_\\d+)", "gim");
A better solution here would be to use a regex literal :
var re = /(page-\d+_\d+)/gim
Don't use the RegExp constructor if the regular expression is constant, regex literals are much more convenient.