Basically, I have an array of strings
var array_strings = ['string1', 'string2', 'string3']
And I would like to know using that array, how could I find every piece of a string that contains something from the array array_strings and remove it.
For example, If I have the string var hello = 'string1 Hello string2'
I would like it to output only Hello and remove string1 and string2.
One possibility would be to join the array of strings you want to remove by |, then construct a regular expression from that, and .replace with '':
const array_strings = ['string1', 'string2', 'string3'];
const pattern = new RegExp(array_strings.join('|'), 'g');
const hello = 'string1 Hello string2';
console.log(hello.replace(pattern, ''));
If you also want to remove the leading/trailing spaces, then use .trim() as well.
Iterate over the array and use the string replace method to remove the strings from the array. We turn the string into a regular expression through the RegExp constructor. This will allow for multiple replaces and the use of a variable within our expression.
var array_strings = ['string1', 'string2', 'string3'],
str = "string1 hello string2",
printStr = (str, removables) => {
for (let removable of removables) {
let re_removable = new RegExp(removable,"g");
str = str.replace(re_removable, "").trim();
}
return str;
};
console.log(printStr(str, array_strings));
If you are going to have only words as per your example with no commas/punctuation etc then you could also simply split the string and then Array.filter it via Array.includes:
const str = 'string1 Hello string2 there string3',
arr = ['string1', 'string2', 'string3'];
console.log(...str.split(' ').filter(x => !arr.includes(x)))
It is a simpler approach in scenario where you do not have complex sentences/string data for which you would need String.replace via RegEx etc.
Related
I have string like below
BANKNIFTY-13-FEB-2020-31200-ce
I want to convert the string to 13-FEB-31200-ce
so I tried below code
str.match(/(.*)-(?:.*)-(?:.*)-(.*)-(?:.*)-(?:.*)/g)
But its returning whole string
Two capture groups is probably the way to go. Now you have two options to use it. One is match which requires you to put the two pieces together
var str = 'BANKNIFTY-13-FEB-2020-31200-ce'
var match = str.match(/[^-]+-(\d{2}-[A-Z]{3}-)\d{4}-(.*)/)
// just reference the two groups
console.log(`${match[1]}${match[2]}`)
// or you can remove the match and join the remaining
match.shift()
console.log(match.join(''))
Or just string replace which you do the concatenation of the two capture groups in one line.
var str = 'BANKNIFTY-13-FEB-2020-31200-ce'
var match = str.replace(/[^-]+-(\d{2}-[A-Z]{3}-)\d{4}-(.*)/, '$1$2')
console.log(match)
Regex doesn't seem to be the most appropriate tool here. Why not use simple .split?
let str = 'BANKNIFTY-13-FEB-2020-31200-ce';
let splits = str.split('-');
let out = [splits[1], splits[2], splits[4], splits[5]].join('-');
console.log(out);
If you really want to use regexp,
let str = 'BANKNIFTY-13-FEB-2020-31200-ce';
let splits = str.match(/[^-]+/g);
let out = [splits[1], splits[2], splits[4], splits[5]].join('-');
console.log(out);
I would not use Regex at all if you know exact positions. Using regex is expensive and should be done differently if there is way. (https://blog.codinghorror.com/regular-expressions-now-you-have-two-problems/)
const strArr = "BANKNIFTY-13-FEB-2020-31200-ce".split("-"); // creates array
strArr.splice(0,1); // remove first item
strArr.splice(2,1); // remove 2020
const finalStr = strArr.join("-");
If the pattern doesn't need to be too specific.
Then just keep it simple and only capture what's needed.
Then glue the captured groups together.
let str = 'BANKNIFTY-13-FEB-2020-31200-ce';
let m = str.match(/^\w+-(\d{1,2}-[A-Z]{3})-\d+-(.*)$/)
let result = m ? m[1]+'-'+m[2] : undefined;
console.log(result);
In this regex, ^ is the start of the string and $ the end of the string.
You can have something like this by capturing groups with regex:
const regex = /(\d{2}\-\w{3})(\-\d{4})(\-\d{5}\-\w{2})/
const text = "BANKNIFTY-13-FEB-2020-31200-ce"
const [, a, b, c] = text.match(regex);
console.log(`${a}${c}`)
I have an expression.
var expression = "Q101='You will have an answer here like a string for instance.'"
I have a regular expression that searches the expression.
var regEx = new regExp(/=|<>|like/)
I want to split the expression using the regular expression.
var result = expression.split(regExp)
This will return the following:
["Q101", "'You will have an answer here ", " a string for instance'"]
This is not what I want.
I should have:
["Q101", "'You will have an answer here like a string for instance'"]
How do I use the regular expression above to split only on the first match?
Since you only want to grab the two parts either side of the first delimiter it might be easier to use String.match and discard the whole match:
var expression = "Q101='You will have an answer here like a string for instance.'";
var parts = expression.match(/^(.*?)(?:=|<>|like)(.*)$/);
parts.shift();
console.log(parts);
expression = "Q101like'This answer uses like twice'";
parts = expression.match(/^(.*?)(?:=|<>|like)(.*)$/);
parts.shift();
console.log(parts);
JavaScript's split method won't quite do what you want, because it will either split on all matches, or stop after N matches. You need an extra step to find the first match, then split once by the first match using a custom function:
function splitMatch(string, match) {
var splitString = match[0];
var result = [
expression.slice(0, match.index),
expression.slice(match.index + splitString.length)
];
return result;
}
var expression = "Q101='You will have an answer here like a string for instance.'"
var regEx = new RegExp(/=|<>|like/)
var match = regEx.exec(expression)
if (match) {
var result = splitMatch(expression, match);
console.log(result);
}
While JavaScript's split method does have an optional limit parameter, it simply discards the parts of the result that make it too long (unlike, e.g. Python's split). To do this in JS, you'll need to split it manually, considering the length of the match —
const exp = "Q101='You will have an answer here like a string for instance.'"
const splitRxp = /=|<>|like/
const splitPos = exp.search(splitRxp)
const splitStr = exp.match(splitRxp)[0]
const result = splitPos != -1 ? (
[
exp.substring(0, splitPos),
exp.substring(splitPos + splitStr.length),
]
) : (
null
);
console.log(result)
I'm attempting to extract strings between occurences of a specific character in a larger string.
For example:
The initial string is:
var str = "http://www.google.com?hello?kitty?test";
I want to be able to store all of the substrings between the question marks as their own variables, such as "hello", "kitty" and "test".
How would I target substrings between different indexes of a specific character using either JavaScript or Regular Expressions?
You could split on ? and use slice passing 1 as the parameter value.
That would give you an array with your values. If you want to create separate variables you could for example get the value by its index var1 = parts[0]
var str = "http://www.google.com?hello?kitty?test";
var parts = str.split('?').slice(1);
console.log(parts);
var var1 = parts[0],
var2 = parts[1],
var3 = parts[2];
console.log(var1);
console.log(var2);
console.log(var3);
Quick note: that URL would be invalid. A question mark ? denotes the beginning of a query string and key/value pairs are generally provided in the form key=value and delimited with an ampersand &.
That being said, if this isn't a problem then why not split on the question mark to obtain an array of values?
var split_values = str.split('?');
//result: [ 'http://www.google.com', 'hello', 'kitty', 'test' ]
Then you could simply grab the individual values from the array, skipping the first element.
I believe this will do it:
var components = "http://www.google.com?hello?kitty?test".split("?");
components.slice(1-components.length) // Returns: [ "hello", "kitty", "test" ]
using Regular Expressions
var reg = /\?([^\?]+)/g;
var s = "http://www.google.com?hello?kitty?test";
var results = null;
while( results = reg.exec(s) ){
console.log(results[1]);
}
The general case is to use RegExp:
var regex1 = new RegExp(/\?.*?(?=\?|$)/,'g'); regex1.lastIndex=0;
str.match(regex1)
Note that this will also get you the leading ? in each clause (no look-behind regexp in Javascript).
Alternatively you can use the sticky flag and run it in a loop:
var regex1 = new RegExp(/.*?\?(.*?)(?=\?|$)/,'y'); regex1.lastIndex=0;
while(str.match(regex1)) {...}
You can take the substring starting from the first question mark, then split by question mark
const str = "http://www.google.com?hello?kitty?test";
const matches = str.substring(str.indexOf('?') + 1).split(/\?/g);
console.log(matches);
I am writing js code to get array of elements after splitting using regular expression.
var data = "ABCXYZ88";
var regexp = "([A-Z]{3})([A-Z]{3}d{2})";
console.log(data.split(regexp));
It returns
[ 'ABCXYZ88' ]
But I am expecting something like
['ABC','XYZ','88']
Any thoughts?
I fixed your regex, then matched it against your string and extracted the relevant capturing groups:
var regex = /([A-Z]{3})([A-Z]{3})(\d{2})/g;
var str = 'ABCXYZ88';
let m = regex.exec(str);
if (m !== null) {
console.log(m.slice(1)); // prints ["ABC", "XYZ", "88"]
}
In your case, I don't think you can split using a regex as you were trying, as there don't seem to be any delimiting characters to match against. For this to work, you'd have to have a string like 'ABC|XYZ|88'; then you could do 'ABC|XYZ|88'.split(/\|/g). (Of course, you wouldn't use a regex for such a simple case.)
Your regexp is not a RegExp object but a string.
Your capturing groups are not correct.
String.prototype.split() is not the function you need. What split() does:
var myString = 'Hello World. How are you doing?';
var splits = myString.split(' ', 3);
console.log(splits); // ["Hello", "World.", "How"]
What you need:
var data = 'ABCXYZ88';
var regexp = /^([A-Z]{3})([A-Z]{3})(\d{2})$/;
var match = data.match(regexp);
console.log(match.slice(1)); // ["ABC", "XYZ", "88"]
Try this. I hope this is what you are looking for.
var reg = data.match(/^([A-Z]{3})([A-Z]{3})(\d{2})$/).slice(1);
https://jsfiddle.net/m5pgpkje/1/
I have a string that looks like this:
{{tagName(21, 'hello, jane','smith')}}
I'm trying to use regex to match() this string to result in:
[0] = tagName
[1] = 21
[2] = 'hello, jane'
[3] = 'smith'
The parameter part of the string can grow. That is to say, it may have more or less parameters and the regex needs to be "greedy" yet knows how to group them up.
I've been trying something like that: ^\{\{([^\(]+)\({1}(.*)\){1}\}\}
But this results in:
[0] = tagName
[1] = 21, 'hello, jane','smith'
What should I do to my regex to get the results I want?
Replace {, }, (, ) with empty string; match [a-z]+, \d+, '.+' followed by , or end of input
var str = "{{tagName(21, 'hello, jane','smith')}}";
var res = str.replace(/\{|\}|\(|\)/g, "")
.match(/([a-z]+)|\d+|('.+')(?=,)|('.+')(?=$)/ig);
console.log(res);
If you're ok with using two regexes, you can return a new array with function name and concat all the parameters onto that array.
With ES6 you can use the spread operator:
const str = "{{tagName(21, 'hello, jane','smith')}}";
const result = str.match(/^\{\{([^\(]+)\({1}(.*)\){1}\}\}/);
console.log([
result[1],
...result[2].match(/^\d+|'.*?'/g)
])
In ES5 you'll have to concat the parameters onto the array containing the function name as its first item:
var str = "{{tagName(21, 'hello, jane','smith')}}";
var result = str.match(/^\{\{([^\(]+)\({1}(.*)\){1}\}\}/);
console.log([result[1]].concat(result[2].match(/^\d+|'.*?'/g)))
In reality, you could concat in ES6, but
So far I've manage to come up with the following:
([A-Za-z]+)|('.*?'|[^',\s\(]+)(?=\s*,|\s*\))
Tested on https://regex101.com