Javascript remove end of a directory in a string [duplicate] - javascript

This question already has answers here:
JS remove everything after the last occurrence of a character [duplicate]
(9 answers)
Closed 3 years ago.
I been looking into split(), slice(), substring() but im not sure they can do what i am looking for.
Basically I want to remove the last sub directory of a string for examble:
Computers/Hard-drive/5GB/Brand
I need to be able to remove the Brand out to something like Computers/Hard-drive/5GB
My solution is
var val = directory.split("/");
var result;
val.forEach(function (dir) {
result = result+"/"+dir;
});
console.log(result);
This returns what I want. But I think this is bad code, I think there must be some way of doing this using only one line. What are other ways of doing this?

You have lots of options.
The regular expression approach
The lastIndexOf approach
The split/join approach
Personally I prefer the simplicity and lack of unnecessary intermediate objects that #2 provides.
1. The regular expression approach
...either as shown by CertainPerformance or a version using replace to replace all characters after the last /.
let str = "Computers/Hard-drive/5GB/Brand";
str = str.replace(/\/[^\/]+$/, "");
console.log(str);
This works just fine if there isn't any slash; it just returns the string unchanged.
2. The lastIndexOf version
let str = "Computers/Hard-drive/5GB/Brand";
const index = str.lastIndexOf("/");
str = str.substring(0, index);
console.log(str);
Note that the above assumes there will be a slash. To not make that assumption, you need to add a guard in case index is -1:
let str = "Computers/Hard-drive/5GB/Brand";
let index = str.lastIndexOf("/");
if (index !== -1) {
str = str.substring(0, index);
}
console.log(str);
str = "Computers";
index = str.lastIndexOf("/");
if (index !== -1) {
str = str.substring(0, index);
}
console.log(str);
3. The split and join approach
...as shown by Nina. (Removed mine when I saw hers, which is much more concise without being harder to read.) Note that Nina's implementation also assumes there will be a slash, you'll need to do a check on the result of split (e.g., is it more than one long) to handle the case where there isn't one.

One option is to use a regular expression: match characters until lookahead matches /, followed by non-/ characters, followed by the end of the string:
const str = 'Computers/Hard-drive/5GB/Brand';
const result = str.match(/.*(?=\/[^/]+$)/)[0];
console.log(result);

You can try with String.prototype.lastIndexOf() and String.prototype.substring()
var directory = 'Computers/Hard-drive/5GB/Brand'
var pos = directory.lastIndexOf("/");
var result = directory.substring(0, pos);
console.log(result);

You could split, slice untile the item before the last one and join the array to a string.
var string = 'Computers/Hard-drive/5GB/Brand',
result = string.split('/').slice(0, -1).join('/');
console.log(result);

Related

Removing last two characters of a string [duplicate]

I have a string, 12345.00, and I would like it to return 12345.0.
I have looked at trim, but it looks like it is only trimming whitespace and slice which I don't see how this would work. Any suggestions?
You can use the substring function:
let str = "12345.00";
str = str.substring(0, str.length - 1);
console.log(str);
This is the accepted answer, but as per the conversations below, the slice syntax is much clearer:
let str = "12345.00";
str = str.slice(0, -1);
console.log(str);
You can use slice! You just have to make sure you know how to use it. Positive #s are relative to the beginning, negative numbers are relative to the end.
js>"12345.00".slice(0,-1)
12345.0
You can use the substring method of JavaScript string objects:
s = s.substring(0, s.length - 4)
It unconditionally removes the last four characters from string s.
However, if you want to conditionally remove the last four characters, only if they are exactly _bar:
var re = /_bar$/;
s.replace(re, "");
The easiest method is to use the slice method of the string, which allows negative positions (corresponding to offsets from the end of the string):
const s = "your string";
const withoutLastFourChars = s.slice(0, -4);
If you needed something more general to remove everything after (and including) the last underscore, you could do the following (so long as s is guaranteed to contain at least one underscore):
const s = "your_string";
const withoutLastChunk = s.slice(0, s.lastIndexOf("_"));
console.log(withoutLastChunk);
For a number like your example, I would recommend doing this over substring:
console.log(parseFloat('12345.00').toFixed(1));
Do note that this will actually round the number, though, which I would imagine is desired but maybe not:
console.log(parseFloat('12345.46').toFixed(1));
Be aware that String.prototype.{ split, slice, substr, substring } operate on UTF-16 encoded strings
None of the previous answers are Unicode-aware.
Strings are encoded as UTF-16 in most modern JavaScript engines, but higher Unicode code points require surrogate pairs, so older, pre-existing string methods operate on UTF-16 code units, not Unicode code points.
See: Do NOT use .split('').
const string = "ẞ🦊";
console.log(string.slice(0, -1)); // "ẞ\ud83e"
console.log(string.substr(0, string.length - 1)); // "ẞ\ud83e"
console.log(string.substring(0, string.length - 1)); // "ẞ\ud83e"
console.log(string.replace(/.$/, "")); // "ẞ\ud83e"
console.log(string.match(/(.*).$/)[1]); // "ẞ\ud83e"
const utf16Chars = string.split("");
utf16Chars.pop();
console.log(utf16Chars.join("")); // "ẞ\ud83e"
In addition, RegExp methods, as suggested in older answers, don’t match line breaks at the end:
const string = "Hello, world!\n";
console.log(string.replace(/.$/, "").endsWith("\n")); // true
console.log(string.match(/(.*).$/) === null); // true
Use the string iterator to iterate characters
Unicode-aware code utilizes the string’s iterator; see Array.from and ... spread.
string[Symbol.iterator] can be used (e.g. instead of string) as well.
Also see How to split Unicode string to characters in JavaScript.
Examples:
const string = "ẞ🦊";
console.log(Array.from(string).slice(0, -1).join("")); // "ẞ"
console.log([
...string
].slice(0, -1).join("")); // "ẞ"
Use the s and u flags on a RegExp
The dotAll or s flag makes . match line break characters, the unicode or u flag enables certain Unicode-related features.
Note that, when using the u flag, you eliminate unnecessary identity escapes, as these are invalid in a u regex, e.g. \[ is fine, as it would start a character class without the backslash, but \: isn’t, as it’s a : with or without the backslash, so you need to remove the backslash.
Examples:
const unicodeString = "ẞ🦊",
lineBreakString = "Hello, world!\n";
console.log(lineBreakString.replace(/.$/s, "").endsWith("\n")); // false
console.log(lineBreakString.match(/(.*).$/s) === null); // false
console.log(unicodeString.replace(/.$/su, "")); // ẞ
console.log(unicodeString.match(/(.*).$/su)[1]); // ẞ
// Now `split` can be made Unicode-aware:
const unicodeCharacterArray = unicodeString.split(/(?:)/su),
lineBreakCharacterArray = lineBreakString.split(/(?:)/su);
unicodeCharacterArray.pop();
lineBreakCharacterArray.pop();
console.log(unicodeCharacterArray.join("")); // "ẞ"
console.log(lineBreakCharacterArray.join("").endsWith("\n")); // false
Note that some graphemes consist of more than one code point, e.g. 🏳️‍🌈 which consists of the sequence 🏳 (U+1F3F3), VS16 (U+FE0F), ZWJ (U+200D), 🌈 (U+1F308).
Here, even Array.from will split this into four “characters”.
Matching those is made easier with the RegExp set notation and properties of strings proposal.
Using JavaScript's slice function:
let string = 'foo_bar';
string = string.slice(0, -4); // Slice off last four characters here
console.log(string);
This could be used to remove '_bar' at end of a string, of any length.
A regular expression is what you are looking for:
let str = "foo_bar";
console.log(str.replace(/_bar$/, ""));
Try this:
const myString = "Hello World!";
console.log(myString.slice(0, -1));
Performance
Today 2020.05.13 I perform tests of chosen solutions on Chrome v81.0, Safari v13.1 and Firefox v76.0 on MacOs High Sierra v10.13.6.
Conclusions
the slice(0,-1)(D) is fast or fastest solution for short and long strings and it is recommended as fast cross-browser solution
solutions based on substring (C) and substr(E) are fast
solutions based on regular expressions (A,B) are slow/medium fast
solutions B, F and G are slow for long strings
solution F is slowest for short strings, G is slowest for long strings
Details
I perform two tests for solutions A, B, C, D, E(ext), F, G(my)
for 8-char short string (from OP question) - you can run it HERE
for 1M long string - you can run it HERE
Solutions are presented in below snippet
function A(str) {
return str.replace(/.$/, '');
}
function B(str) {
return str.match(/(.*).$/)[1];
}
function C(str) {
return str.substring(0, str.length - 1);
}
function D(str) {
return str.slice(0, -1);
}
function E(str) {
return str.substr(0, str.length - 1);
}
function F(str) {
let s= str.split("");
s.pop();
return s.join("");
}
function G(str) {
let s='';
for(let i=0; i<str.length-1; i++) s+=str[i];
return s;
}
// ---------
// TEST
// ---------
let log = (f)=>console.log(`${f.name}: ${f("12345.00")}`);
[A,B,C,D,E,F,G].map(f=>log(f));
This snippet only presents soutions
Here are example results for Chrome for short string
Use regex:
let aStr = "12345.00";
aStr = aStr.replace(/.$/, '');
console.log(aStr);
How about:
let myString = "12345.00";
console.log(myString.substring(0, myString.length - 1));
1. (.*), captures any character multiple times:
console.log("a string".match(/(.*).$/)[1]);
2. ., matches last character, in this case:
console.log("a string".match(/(.*).$/));
3. $, matches the end of the string:
console.log("a string".match(/(.*).{2}$/)[1]);
https://stackoverflow.com/questions/34817546/javascript-how-to-delete-last-two-characters-in-a-string
Just use trim if you don't want spaces
"11.01 °C".slice(0,-2).trim()
Here is an alternative that i don't think i've seen in the other answers, just for fun.
var strArr = "hello i'm a string".split("");
strArr.pop();
document.write(strArr.join(""));
Not as legible or simple as slice or substring but does allow you to play with the string using some nice array methods, so worth knowing.
debris = string.split("_") //explode string into array of strings indexed by "_"
debris.pop(); //pop last element off the array (which you didn't want)
result = debris.join("_"); //fuse the remainng items together like the sun
If you want to do generic rounding of floats, instead of just trimming the last character:
var float1 = 12345.00,
float2 = 12345.4567,
float3 = 12345.982;
var MoreMath = {
/**
* Rounds a value to the specified number of decimals
* #param float value The value to be rounded
* #param int nrDecimals The number of decimals to round value to
* #return float value rounded to nrDecimals decimals
*/
round: function (value, nrDecimals) {
var x = nrDecimals > 0 ? 10 * parseInt(nrDecimals, 10) : 1;
return Math.round(value * x) / x;
}
}
MoreMath.round(float1, 1) => 12345.0
MoreMath.round(float2, 1) => 12345.5
MoreMath.round(float3, 1) => 12346.0
EDIT: Seems like there exists a built in function for this, as Paolo points out. That solution is obviously much cleaner than mine. Use parseFloat followed by toFixed
if(str.substring(str.length - 4) == "_bar")
{
str = str.substring(0, str.length - 4);
}
Via slice(indexStart, indexEnd) method - note, this does NOT CHANGE the existing string, it creates a copy and changes the copy.
console.clear();
let str = "12345.00";
let a = str.slice(0, str.length -1)
console.log(a, "<= a");
console.log(str, "<= str is NOT changed");
Via Regular Expression method - note, this does NOT CHANGE the existing string, it creates a copy and changes the copy.
console.clear();
let regExp = /.$/g
let b = str.replace(regExp,"")
console.log(b, "<= b");
console.log(str, "<= str is NOT changed");
Via array.splice() method -> this only works on arrays, and it CHANGES, the existing array (so careful with this one), you'll need to convert a string to an array first, then back.
console.clear();
let str = "12345.00";
let strToArray = str.split("")
console.log(strToArray, "<= strToArray");
let spliceMethod = strToArray.splice(str.length-1, 1)
str = strToArray.join("")
console.log(str, "<= str is changed now");
In cases where you want to remove something that is close to the end of a string (in case of variable sized strings) you can combine slice() and substr().
I had a string with markup, dynamically built, with a list of anchor tags separated by comma. The string was something like:
var str = "<a>text 1,</a><a>text 2,</a><a>text 2.3,</a><a>text abc,</a>";
To remove the last comma I did the following:
str = str.slice(0, -5) + str.substr(-4);
You can, in fact, remove the last arr.length - 2 items of an array using arr.length = 2, which if the array length was 5, would remove the last 3 items.
Sadly, this does not work for strings, but we can use split() to split the string, and then join() to join the string after we've made any modifications.
var str = 'string'
String.prototype.removeLast = function(n) {
var string = this.split('')
string.length = string.length - n
return string.join('')
}
console.log(str.removeLast(3))
Try to use toFixed
const str = "12345.00";
return (+str).toFixed(1);
Try this:
<script>
var x="foo_foo_foo_bar";
for (var i=0; i<=x.length; i++) {
if (x[i]=="_" && x[i+1]=="b") {
break;
}
else {
document.write(x[i]);
}
}
</script>
You can also try the live working example on http://jsfiddle.net/informativejavascript/F7WTn/87/.
#Jason S:
You can use slice! You just have to
make sure you know how to use it.
Positive #s are relative to the
beginning, negative numbers are
relative to the end.
js>"12345.00".slice(0,-1)
12345.0
Sorry for my graphomany but post was tagged 'jquery' earlier. So, you can't use slice() inside jQuery because slice() is jQuery method for operations with DOM elements, not substrings ...
In other words answer #Jon Erickson suggest really perfect solution.
However, your method will works out of jQuery function, inside simple Javascript.
Need to say due to last discussion in comments, that jQuery is very much more often renewable extension of JS than his own parent most known ECMAScript.
Here also exist two methods:
as our:
string.substring(from,to) as plus if 'to' index nulled returns the rest of string. so:
string.substring(from) positive or negative ...
and some other - substr() - which provide range of substring and 'length' can be positive only:
string.substr(start,length)
Also some maintainers suggest that last method string.substr(start,length) do not works or work with error for MSIE.
Use substring to get everything to the left of _bar. But first you have to get the instr of _bar in the string:
str.substring(3, 7);
3 is that start and 7 is the length.

Get multiple substring between two characters javascript [duplicate]

This question already has answers here:
Regular expression to get a string between two strings in Javascript
(13 answers)
Closed 2 years ago.
I'm taking this post as reference where they suggest this solution:
Current
Str = 'MyLongString:StringIWant;'
Desired Output
newStr = 'StringIWant'
Solution
var mySubString = str.substring(
str.lastIndexOf(":") + 1,
str.lastIndexOf(";")
);
but what if i have multiple incidence? in my case i have a long text, lets say:
str = 'MyLongString has :multiple; words that i :need; to :extract;'
New desired output:
strarray = ["multiple","need","extract"]
When i apply the suggested solution its just getting the last word "extract"
This is one way of doing it, running a loop from start of the string to the end and using indexOf and substring to get the desired result
const str = 'MyLongString has :multiple; words that i :need; to :extract;';
function extractWords(str) {
const words = [];
for (let i = 0; i < str.length; i++) {
if (str.charAt(i) === ':') {
const stopIndex = str.indexOf(';', i);
if (stopIndex !== -1)
words.push(str.substring(i + 1, stopIndex));
}
}
return words;
}
console.log(extractWords(str));
The linked suggestion is actually using a string function instead of a regular pattern; a simple pattern like /:\w+;/g gives us all desired words, thanks to the /g flag.
We can get rid of the pre- and postfix using lookarounds, however, those may not work in all JavaScript environments (but actually it is less of a problem now since all major browsers support the lookbehind (?<=..) operator in their latest versions, and the lookahead (?=..) is supported since forever).
str = 'MyLongString has :multiple; words that i :need; to :extract;'
let result = str.match(/:\w+;/g) || [];
console.log(result);
let result2 = str.match(/(?<=:)\w+(?=;)/g) || [];
console.log(result2);

Plain Javascript Split String UPPER from lower case

i'm trying to split a String which contains an Uppercase Part + a Lowercase Part in Javascript (ES5). The String always looks like "UPPERlower".
Here's what i currently use
"ABCabc".match(/^[A-Z]+/g).concat("ABCabc".match(/[a-z]+$/g)) //result is ["ABC", "abc"]
Is there a cleaner code to achieve this?
EDIT:
Ori Drori's answer and mplungjan's answer are both correct for my Problem.
You can use | to match either the uppercase or lowercase sequence:
var result = "ABCabc".match(/[A-Z]+|[a-z]+/g)
console.log(result);
Destructuring is the modern way
const s="UPPERlower";
let [,upper, lower] =/([A-Z]+)([a-z]+)/g.exec(s);
console.log(upper,lower);
Looping - NOTE: What is the difference between RegExp’s exec() function and String’s match() function?
const s = "UPPERlower UPlow 123 lowUP UPPlowe";
// Note:above will produce low UP using .match(/[A-Z]+|[a-z]+/g) instead of capturing
const re = /([A-Z]+)([a-z]+)/g;
while (match = re.exec(s)) {
[, upper, lower] = match;
console.log(upper, lower)
}
Older way:
var parts=/([A-Z]+)([a-z]+)/g.exec("UPPERlower");
console.log(parts[1],parts[2]);

trim certain number of characters from end of javascript string [duplicate]

I have a string, 12345.00, and I would like it to return 12345.0.
I have looked at trim, but it looks like it is only trimming whitespace and slice which I don't see how this would work. Any suggestions?
You can use the substring function:
let str = "12345.00";
str = str.substring(0, str.length - 1);
console.log(str);
This is the accepted answer, but as per the conversations below, the slice syntax is much clearer:
let str = "12345.00";
str = str.slice(0, -1);
console.log(str);
You can use slice! You just have to make sure you know how to use it. Positive #s are relative to the beginning, negative numbers are relative to the end.
js>"12345.00".slice(0,-1)
12345.0
You can use the substring method of JavaScript string objects:
s = s.substring(0, s.length - 4)
It unconditionally removes the last four characters from string s.
However, if you want to conditionally remove the last four characters, only if they are exactly _bar:
var re = /_bar$/;
s.replace(re, "");
The easiest method is to use the slice method of the string, which allows negative positions (corresponding to offsets from the end of the string):
const s = "your string";
const withoutLastFourChars = s.slice(0, -4);
If you needed something more general to remove everything after (and including) the last underscore, you could do the following (so long as s is guaranteed to contain at least one underscore):
const s = "your_string";
const withoutLastChunk = s.slice(0, s.lastIndexOf("_"));
console.log(withoutLastChunk);
For a number like your example, I would recommend doing this over substring:
console.log(parseFloat('12345.00').toFixed(1));
Do note that this will actually round the number, though, which I would imagine is desired but maybe not:
console.log(parseFloat('12345.46').toFixed(1));
Be aware that String.prototype.{ split, slice, substr, substring } operate on UTF-16 encoded strings
None of the previous answers are Unicode-aware.
Strings are encoded as UTF-16 in most modern JavaScript engines, but higher Unicode code points require surrogate pairs, so older, pre-existing string methods operate on UTF-16 code units, not Unicode code points.
See: Do NOT use .split('').
const string = "ẞ🦊";
console.log(string.slice(0, -1)); // "ẞ\ud83e"
console.log(string.substr(0, string.length - 1)); // "ẞ\ud83e"
console.log(string.substring(0, string.length - 1)); // "ẞ\ud83e"
console.log(string.replace(/.$/, "")); // "ẞ\ud83e"
console.log(string.match(/(.*).$/)[1]); // "ẞ\ud83e"
const utf16Chars = string.split("");
utf16Chars.pop();
console.log(utf16Chars.join("")); // "ẞ\ud83e"
In addition, RegExp methods, as suggested in older answers, don’t match line breaks at the end:
const string = "Hello, world!\n";
console.log(string.replace(/.$/, "").endsWith("\n")); // true
console.log(string.match(/(.*).$/) === null); // true
Use the string iterator to iterate characters
Unicode-aware code utilizes the string’s iterator; see Array.from and ... spread.
string[Symbol.iterator] can be used (e.g. instead of string) as well.
Also see How to split Unicode string to characters in JavaScript.
Examples:
const string = "ẞ🦊";
console.log(Array.from(string).slice(0, -1).join("")); // "ẞ"
console.log([
...string
].slice(0, -1).join("")); // "ẞ"
Use the s and u flags on a RegExp
The dotAll or s flag makes . match line break characters, the unicode or u flag enables certain Unicode-related features.
Note that, when using the u flag, you eliminate unnecessary identity escapes, as these are invalid in a u regex, e.g. \[ is fine, as it would start a character class without the backslash, but \: isn’t, as it’s a : with or without the backslash, so you need to remove the backslash.
Examples:
const unicodeString = "ẞ🦊",
lineBreakString = "Hello, world!\n";
console.log(lineBreakString.replace(/.$/s, "").endsWith("\n")); // false
console.log(lineBreakString.match(/(.*).$/s) === null); // false
console.log(unicodeString.replace(/.$/su, "")); // ẞ
console.log(unicodeString.match(/(.*).$/su)[1]); // ẞ
// Now `split` can be made Unicode-aware:
const unicodeCharacterArray = unicodeString.split(/(?:)/su),
lineBreakCharacterArray = lineBreakString.split(/(?:)/su);
unicodeCharacterArray.pop();
lineBreakCharacterArray.pop();
console.log(unicodeCharacterArray.join("")); // "ẞ"
console.log(lineBreakCharacterArray.join("").endsWith("\n")); // false
Note that some graphemes consist of more than one code point, e.g. 🏳️‍🌈 which consists of the sequence 🏳 (U+1F3F3), VS16 (U+FE0F), ZWJ (U+200D), 🌈 (U+1F308).
Here, even Array.from will split this into four “characters”.
Matching those is made easier with the RegExp set notation and properties of strings proposal.
Using JavaScript's slice function:
let string = 'foo_bar';
string = string.slice(0, -4); // Slice off last four characters here
console.log(string);
This could be used to remove '_bar' at end of a string, of any length.
A regular expression is what you are looking for:
let str = "foo_bar";
console.log(str.replace(/_bar$/, ""));
Try this:
const myString = "Hello World!";
console.log(myString.slice(0, -1));
Performance
Today 2020.05.13 I perform tests of chosen solutions on Chrome v81.0, Safari v13.1 and Firefox v76.0 on MacOs High Sierra v10.13.6.
Conclusions
the slice(0,-1)(D) is fast or fastest solution for short and long strings and it is recommended as fast cross-browser solution
solutions based on substring (C) and substr(E) are fast
solutions based on regular expressions (A,B) are slow/medium fast
solutions B, F and G are slow for long strings
solution F is slowest for short strings, G is slowest for long strings
Details
I perform two tests for solutions A, B, C, D, E(ext), F, G(my)
for 8-char short string (from OP question) - you can run it HERE
for 1M long string - you can run it HERE
Solutions are presented in below snippet
function A(str) {
return str.replace(/.$/, '');
}
function B(str) {
return str.match(/(.*).$/)[1];
}
function C(str) {
return str.substring(0, str.length - 1);
}
function D(str) {
return str.slice(0, -1);
}
function E(str) {
return str.substr(0, str.length - 1);
}
function F(str) {
let s= str.split("");
s.pop();
return s.join("");
}
function G(str) {
let s='';
for(let i=0; i<str.length-1; i++) s+=str[i];
return s;
}
// ---------
// TEST
// ---------
let log = (f)=>console.log(`${f.name}: ${f("12345.00")}`);
[A,B,C,D,E,F,G].map(f=>log(f));
This snippet only presents soutions
Here are example results for Chrome for short string
Use regex:
let aStr = "12345.00";
aStr = aStr.replace(/.$/, '');
console.log(aStr);
How about:
let myString = "12345.00";
console.log(myString.substring(0, myString.length - 1));
1. (.*), captures any character multiple times:
console.log("a string".match(/(.*).$/)[1]);
2. ., matches last character, in this case:
console.log("a string".match(/(.*).$/));
3. $, matches the end of the string:
console.log("a string".match(/(.*).{2}$/)[1]);
https://stackoverflow.com/questions/34817546/javascript-how-to-delete-last-two-characters-in-a-string
Just use trim if you don't want spaces
"11.01 °C".slice(0,-2).trim()
Here is an alternative that i don't think i've seen in the other answers, just for fun.
var strArr = "hello i'm a string".split("");
strArr.pop();
document.write(strArr.join(""));
Not as legible or simple as slice or substring but does allow you to play with the string using some nice array methods, so worth knowing.
debris = string.split("_") //explode string into array of strings indexed by "_"
debris.pop(); //pop last element off the array (which you didn't want)
result = debris.join("_"); //fuse the remainng items together like the sun
If you want to do generic rounding of floats, instead of just trimming the last character:
var float1 = 12345.00,
float2 = 12345.4567,
float3 = 12345.982;
var MoreMath = {
/**
* Rounds a value to the specified number of decimals
* #param float value The value to be rounded
* #param int nrDecimals The number of decimals to round value to
* #return float value rounded to nrDecimals decimals
*/
round: function (value, nrDecimals) {
var x = nrDecimals > 0 ? 10 * parseInt(nrDecimals, 10) : 1;
return Math.round(value * x) / x;
}
}
MoreMath.round(float1, 1) => 12345.0
MoreMath.round(float2, 1) => 12345.5
MoreMath.round(float3, 1) => 12346.0
EDIT: Seems like there exists a built in function for this, as Paolo points out. That solution is obviously much cleaner than mine. Use parseFloat followed by toFixed
if(str.substring(str.length - 4) == "_bar")
{
str = str.substring(0, str.length - 4);
}
Via slice(indexStart, indexEnd) method - note, this does NOT CHANGE the existing string, it creates a copy and changes the copy.
console.clear();
let str = "12345.00";
let a = str.slice(0, str.length -1)
console.log(a, "<= a");
console.log(str, "<= str is NOT changed");
Via Regular Expression method - note, this does NOT CHANGE the existing string, it creates a copy and changes the copy.
console.clear();
let regExp = /.$/g
let b = str.replace(regExp,"")
console.log(b, "<= b");
console.log(str, "<= str is NOT changed");
Via array.splice() method -> this only works on arrays, and it CHANGES, the existing array (so careful with this one), you'll need to convert a string to an array first, then back.
console.clear();
let str = "12345.00";
let strToArray = str.split("")
console.log(strToArray, "<= strToArray");
let spliceMethod = strToArray.splice(str.length-1, 1)
str = strToArray.join("")
console.log(str, "<= str is changed now");
In cases where you want to remove something that is close to the end of a string (in case of variable sized strings) you can combine slice() and substr().
I had a string with markup, dynamically built, with a list of anchor tags separated by comma. The string was something like:
var str = "<a>text 1,</a><a>text 2,</a><a>text 2.3,</a><a>text abc,</a>";
To remove the last comma I did the following:
str = str.slice(0, -5) + str.substr(-4);
You can, in fact, remove the last arr.length - 2 items of an array using arr.length = 2, which if the array length was 5, would remove the last 3 items.
Sadly, this does not work for strings, but we can use split() to split the string, and then join() to join the string after we've made any modifications.
var str = 'string'
String.prototype.removeLast = function(n) {
var string = this.split('')
string.length = string.length - n
return string.join('')
}
console.log(str.removeLast(3))
Try to use toFixed
const str = "12345.00";
return (+str).toFixed(1);
Try this:
<script>
var x="foo_foo_foo_bar";
for (var i=0; i<=x.length; i++) {
if (x[i]=="_" && x[i+1]=="b") {
break;
}
else {
document.write(x[i]);
}
}
</script>
You can also try the live working example on http://jsfiddle.net/informativejavascript/F7WTn/87/.
#Jason S:
You can use slice! You just have to
make sure you know how to use it.
Positive #s are relative to the
beginning, negative numbers are
relative to the end.
js>"12345.00".slice(0,-1)
12345.0
Sorry for my graphomany but post was tagged 'jquery' earlier. So, you can't use slice() inside jQuery because slice() is jQuery method for operations with DOM elements, not substrings ...
In other words answer #Jon Erickson suggest really perfect solution.
However, your method will works out of jQuery function, inside simple Javascript.
Need to say due to last discussion in comments, that jQuery is very much more often renewable extension of JS than his own parent most known ECMAScript.
Here also exist two methods:
as our:
string.substring(from,to) as plus if 'to' index nulled returns the rest of string. so:
string.substring(from) positive or negative ...
and some other - substr() - which provide range of substring and 'length' can be positive only:
string.substr(start,length)
Also some maintainers suggest that last method string.substr(start,length) do not works or work with error for MSIE.
Use substring to get everything to the left of _bar. But first you have to get the instr of _bar in the string:
str.substring(3, 7);
3 is that start and 7 is the length.

How to split the values in JavaScript

I have to split the values using JavaScript and want to find the last occuring slash / from a string and replace the contents after the last slash / For example:
var word = "www.abc/def/ghf/ijk/**default.aspx**";
should become
var word ="www.abc/def/ghf/ijk/**replacement**";
The number of slashes may vary each time.
Try using regexp:
"www.abc/def/ghf/ijk/default.aspx".replace(/\/[^\/]+$/, "/replacement");
An alternative without regular expression (I just remembered lastIndexOf() method)
var word = "www.abc/def/ghf/ijk/default.aspx";
word = word.substring(0, word.lastIndexOf("/")) + "/replacement";
You can array split on '/', then pop the last element off the array, and rejoin.
word = word.split('/');
word.pop();
word = word.join('/') + replacement;
How about the KISS principle?
var word = "www.abc/def/ghf/ijk/default.aspx";
word = word.substring(0, word.lastIndexOf("/")) + "/replacement";
What about using a combination of the join() and split() functions?
var word = "www.abc/def/ghf/ijk/default.aspx";
// split the word using a `/` as a delimiter
wordParts = word.split('/');
// replace the last element of the array
wordParts[wordParts.length-1] = 'replacement';
// join the array back to a string.
var finalWord = wordParts.join('/');
The number of slashes doesn't matter here because all that is done is to split the string at every instance of the delimiter (in this case a slash).
Here is a working demo
Use regexp or arrays, something like:
[].splice.call(word = word.split('/'), -1, 1, 'replacement');
word = word.join('/');

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