Related
Can someone please help me to write a JS method which takes a String value like
/Content/blockDiagram/0/bundle/0/selectedBundle
/Content/blockDiagram/1/bundle/1/selectedBundle
/Content/blockDiagram/0/bundle
and convert it to
/Content/blockDiagram[1]/bundle[1]/selectedBundle
/Content/blockDiagram[2]/bundle[2]/selectedBundle
/Content/blockDiagram[1]/bundle
It is basically taking the number in the path and increment it by 1 and then changing the structure of the string.
My attempt
function setReplicantPartListOptions(list) {
list = "/" + list;
var index = list.lastIndexOf("/");
var tempString = list.substring(0, index);
var index2 = tempString.lastIndexOf("/");
var initialString = list.substring(0, index2);
var result = tempString.substring(index2 + 1, index) var middlevalue = parseFloat(result) + 1
var lastString = list.substring(index, list.length);
list = initialString + "[" + middlevalue + "]" + lastString;
return list;
}
simple regular expression with capture group with replace
var str = "/Content/blockDiagram/0/bundle/0/selectedBundle"
var updated = str.replace(/\/(\d+)/g, function (m, num) {
var next = +num + 1; // convert string to number and add one
return "[" + next + "]"; //return the new string
})
console.log(updated)
String.replace(RegExp, callback(match, contents)) is the callback version of String.replace().
In my case, the first parameter of callback function is the result/match. It takes the match and converts it to number using + operator, and then increment it by one. Finally, I add [ ] around the value and return it!
let str = "/Content/blockDiagram/0/bundle/0/selectedBundle"
console.log(
str.replace(/\b\d+\b/g, match => `[${ +match + 1 }]`)
);
var str = "/Content/blockDiagram/0/bundle/0/selectedBundle"
console.log(
str.replace(/\/(\d+)\//g, function(_,num) { return `[${++num}]`})
)
I have a string with certain amount of commas. I want to find index of 5-th comma and then splice it. How can I do it?
Like this string: "This, is, my, javascript, string, to, present"
Turn into this: "This, is, my, javascript, string to, present"
var str = "This, is, my, javascript, string, to, present";
var i = 0, c = 5; // for flexibility c could be any number (3 for the third, ...)
while((i = str.indexOf(',', i + 1)) !== -1 && --c) // look for the fifth comma if any
;
if(i != -1) // if there is a fifth comma
str = str.substr(0, i) + str.substr(i + 1); // then remove it
console.log(str);
You could splice the array after slitting the string.
var string = 'This, is, my, javascript, string, to, present',
pos = 5,
temp = string.split(',');
temp.splice(pos -1, 0, temp.splice(pos - 1, 2).join(''));
console.log(temp.join(','));
1) The solution using String.prototype.replace() function:
var str = "This, is, my, javascript, string, to, present",
count = 0;
spliced = str.replace(/,/g, function(m){
return (++count == 5)? '' : m;
});
console.log(spliced);
2) The alternative solution using String.prototype.split() and Array.prototype.slice() functions:
var str = "This, is, my, javascript, string, to, present",
parts = str.split(','),
spliced = (parts.length > 5)? parts.slice(0, 5).join(',') + parts.slice(5).join(',') : parts.join(',');
console.log(spliced);
Try this;
function removeCharacterAtIndex(value, index) {
return value.substring(0, index) + value.substring(index + 1);
}
var input = "This, is, my, javascript, string, to, present";
console.log(removeCharacterAtIndex(input, 32));
var myStringArray = myString.split("");
var count = 0;
myStringArray.forEach(function(item, index){
if(item === ','){
count ++;
}
if (count ===5){
indexOf5thcomma = index;
}
});
myStringArray.splice(indexOf5thcomma, 1);
myString = myStringArray.join("");
Try something like this?
function getPosition(string, subString, index) {
return string.split(subString, index).join(subString).length;
}
Usage:
var myString = "This, is, my, javascript, string, to, present";
getPosition(myString, ',', 5);
Use some tricks on String.prototype.replace:
function replace (str, word, pos) {
let cnt = 0
return str.replace(word, word => ++cnt == pos ? '' : word)
}
console.log(replace("This, is, my, javascript, string, to, present", ',', 5)
The second argument of String.prototype.replace can be a function, which receives a matched string and returns the string to be place into the position. So we can use a scoped counter to determine which comma is to be removed.
Try like this:
var myString = "This, is, my, javascript, string, to, present";
var counter = 0;
myString = myString.split(""); // string to array
// find and replace 5th comma in array using counter
for (var i = 0; i < myString.length; i++) {
if (myString[i] === ",") {
counter++;
if (counter === 5) {
myString.splice(i, 1);
}
}
}
myString = myString.join(""); // array to string
string[index] = 'a'
seems didn't work, it cannot change the string.
Why's that and are there any articles about this?
here an example of a function that would solve this
function replaceAt(string, index, newValue) {
if(index >= string.length || index < 0) {return false;}
var start = string.substr(0,index);
var finish = string.substr(index+1);
return start + newValue.toString() + finish;
}
Strings are not arrays but you can convert them into arrays and then join them back into strings.
var strArray = string.split("");
strArray[index] = 'a';
string = strArray.join("");
I have this string:
0000000020C90037:TEMP:data
I need this string:
TEMP:data.
With PHP I would do this:
$str = '0000000020C90037:TEMP:data';
$arr = explode(':', $str);
$var = $arr[1].':'.$arr[2];
How do I effectively explode a string in JavaScript the way it works in PHP?
This is a direct conversion from your PHP code:
//Loading the variable
var mystr = '0000000020C90037:TEMP:data';
//Splitting it with : as the separator
var myarr = mystr.split(":");
//Then read the values from the array where 0 is the first
//Since we skipped the first element in the array, we start at 1
var myvar = myarr[1] + ":" + myarr[2];
// Show the resulting value
console.log(myvar);
// 'TEMP:data'
String.prototype.explode = function (separator, limit)
{
const array = this.split(separator);
if (limit !== undefined && array.length >= limit)
{
array.push(array.splice(limit - 1).join(separator));
}
return array;
};
Should mimic PHP's explode() function exactly.
'a'.explode('.', 2); // ['a']
'a.b'.explode('.', 2); // ['a', 'b']
'a.b.c'.explode('.', 2); // ['a', 'b.c']
You don't need to split. You can use indexOf and substr:
str = str.substr(str.indexOf(':')+1);
But the equivalent to explode would be split.
Looks like you want split
Try this:
arr = str.split (":");
create's an object :
// create a data object to store the information below.
var data = new Object();
// this could be a suffix of a url string.
var string = "?id=5&first=John&last=Doe";
// this will now loop through the string and pull out key value pairs seperated
// by the & character as a combined string, in addition it passes up the ? mark
var pairs = string.substring(string.indexOf('?')+1).split('&');
for(var key in pairs)
{
var value = pairs[key].split("=");
data[value[0]] = value[1];
}
// creates this object
var data = {"id":"5", "first":"John", "last":"Doe"};
// you can then access the data like this
data.id = "5";
data.first = "John";
data.last = "Doe";
Use String.split
"0000000020C90037:TEMP:data".split(':')
If you like php, take a look at php.JS - JavaScript explode
Or in normal JavaScript functionality:
`
var vInputString = "0000000020C90037:TEMP:data";
var vArray = vInputString.split(":");
var vRes = vArray[1] + ":" + vArray[2]; `
console.log(('0000000020C90037:TEMP:data').split(":").slice(1).join(':'))
outputs: TEMP:data
.split() will disassemble a string into parts
.join() reassembles the array back to a string
when you want the array without it's first item, use .slice(1)
With no intentions to critique John Hartsock, just in case the number of delimiters may vary for anyone using the given code, I would formally suggest to use this instead...
var mystr = '0000000020C90037:TEMP:data';
var myarr = mystr.split(":");
var arrlen = myarr.length;
var myvar = myarr[arrlen-2] + ":" + myarr[arrlen-1];
var str = '0000000020C90037:TEMP:data'; // str = "0000000020C90037:TEMP:data"
str = str.replace(/^[^:]+:/, ""); // str = "TEMP:data"
Just a little addition to psycho brm´s answer (his version doesn't work in IE<=8).
This code is cross-browser compatible:
function explode (s, separator, limit)
{
var arr = s.split(separator);
if (limit) {
arr.push(arr.splice(limit-1, (arr.length-(limit-1))).join(separator));
}
return arr;
}
I used slice, split and join
You can just write one line of code
let arrys = (str.split(":").slice(1)).join(":");
So I know that this post is pretty old, but I figured I may as well add a function that has helped me over the years. Why not just remake the explode function using split as mentioned above? Well here it is:
function explode(str,begin,end)
{
t=str.split(begin);
t=t[1].split(end);
return t[0];
}
This function works well if you are trying to get the values between two values. For instance:
data='[value]insertdataherethatyouwanttoget[/value]';
If you were interested in getting the information from between the two [values] "tags", you could use the function like the following.
out=explode(data,'[value]','[/value]');
//Variable out would display the string: insertdataherethatyouwanttoget
But let's say you don't have those handy "tags" like the example above displayed. No matter.
out=explode(data,'insert','wanttoget');
//Now out would display the string: dataherethatyou
Wana see it in action? Click here.
var str = "helloword~this~is~me";
var exploded = str.splice(~);
the exploded variable will return array and you can access elements of the array be accessing it true exploded[nth] where nth is the index of the value you want to get
try like this,
ans = str.split (":");
And you can use two parts of the string like,
ans[0] and ans[1]
If you want to defined your own function, try this:
function explode (delimiter, string, limit) {
if (arguments.length < 2 ||
typeof delimiter === 'undefined' ||
typeof string === 'undefined') {
return null
}
if (delimiter === '' ||
delimiter === false ||
delimiter === null) {
return false
}
if (typeof delimiter === 'function' ||
typeof delimiter === 'object' ||
typeof string === 'function' ||
typeof string === 'object') {
return {
0: ''
}
}
if (delimiter === true) {
delimiter = '1'
}
// Here we go...
delimiter += ''
string += ''
var s = string.split(delimiter)
if (typeof limit === 'undefined') return s
// Support for limit
if (limit === 0) limit = 1
// Positive limit
if (limit > 0) {
if (limit >= s.length) {
return s
}
return s
.slice(0, limit - 1)
.concat([s.slice(limit - 1)
.join(delimiter)
])
}
// Negative limit
if (-limit >= s.length) {
return []
}
s.splice(s.length + limit)
return s
}
Taken from: http://locutus.io/php/strings/explode/
I have a string, let's say Hello world and I need to replace the char at index 3. How can I replace a char by specifying a index?
var str = "hello world";
I need something like
str.replaceAt(0,"h");
In JavaScript, strings are immutable, which means the best you can do is to create a new string with the changed content and assign the variable to point to it.
You'll need to define the replaceAt() function yourself:
String.prototype.replaceAt = function(index, replacement) {
return this.substring(0, index) + replacement + this.substring(index + replacement.length);
}
And use it like this:
var hello = "Hello World";
alert(hello.replaceAt(2, "!!")); // He!!o World
There is no replaceAt function in JavaScript. You can use the following code to replace any character in any string at specified position:
function rep() {
var str = 'Hello World';
str = setCharAt(str,4,'a');
alert(str);
}
function setCharAt(str,index,chr) {
if(index > str.length-1) return str;
return str.substring(0,index) + chr + str.substring(index+1);
}
<button onclick="rep();">click</button>
You can't. Take the characters before and after the position and concat into a new string:
var s = "Hello world";
var index = 3;
s = s.substring(0, index) + 'x' + s.substring(index + 1);
str = str.split('');
str[3] = 'h';
str = str.join('');
There are lot of answers here, and all of them are based on two methods:
METHOD1: split the string using two substrings and stuff the character between them
METHOD2: convert the string to character array, replace one array member and join it
Personally, I would use these two methods in different cases. Let me explain.
#FabioPhms: Your method was the one I initially used and I was afraid that it is bad on string with lots of characters. However, question is what's a lot of characters? I tested it on 10 "lorem ipsum" paragraphs and it took a few milliseconds. Then I tested it on 10 times larger string - there was really no big difference. Hm.
#vsync, #Cory Mawhorter: Your comments are unambiguous; however, again, what is a large string? I agree that for 32...100kb performance should better and one should use substring-variant for this one operation of character replacement.
But what will happen if I have to make quite a few replacements?
I needed to perform my own tests to prove what is faster in that case. Let's say we have an algorithm that will manipulate a relatively short string that consists of 1000 characters. We expect that in average each character in that string will be replaced ~100 times. So, the code to test something like this is:
var str = "... {A LARGE STRING HERE} ...";
for(var i=0; i<100000; i++)
{
var n = '' + Math.floor(Math.random() * 10);
var p = Math.floor(Math.random() * 1000);
// replace character *n* on position *p*
}
I created a fiddle for this, and it's here.
There are two tests, TEST1 (substring) and TEST2 (array conversion).
Results:
TEST1: 195ms
TEST2: 6ms
It seems that array conversion beats substring by 2 orders of magnitude! So - what the hell happened here???
What actually happens is that all operations in TEST2 are done on array itself, using assignment expression like strarr2[p] = n. Assignment is really fast compared to substring on a large string, and its clear that it's going to win.
So, it's all about choosing the right tool for the job. Again.
Work with vectors is usually most effective to contact String.
I suggest the following function:
String.prototype.replaceAt=function(index, char) {
var a = this.split("");
a[index] = char;
return a.join("");
}
Run this snippet:
String.prototype.replaceAt=function(index, char) {
var a = this.split("");
a[index] = char;
return a.join("");
}
var str = "hello world";
str = str.replaceAt(3, "#");
document.write(str);
In Javascript strings are immutable so you have to do something like
var x = "Hello world"
x = x.substring(0, i) + 'h' + x.substring(i+1);
To replace the character in x at i with 'h'
function dothis() {
var x = document.getElementById("x").value;
var index = document.getElementById("index").value;
var text = document.getElementById("text").value;
var length = document.getElementById("length").value;
var arr = x.split("");
arr.splice(index, length, text);
var result = arr.join("");
document.getElementById('output').innerHTML = result;
console.log(result);
}
dothis();
<input id="x" type="text" value="White Dog" placeholder="Enter Text" />
<input id="index" type="number" min="0"value="6" style="width:50px" placeholder="index" />
<input id="length" type="number" min="0"value="1" style="width:50px" placeholder="length" />
<input id="text" type="text" value="F" placeholder="New character" />
<br>
<button id="submit" onclick="dothis()">Run</button>
<p id="output"></p>
This method is good for small length strings but may be slow for larger text.
var x = "White Dog";
var arr = x.split(""); // ["W", "h", "i", "t", "e", " ", "D", "o", "g"]
arr.splice(6, 1, 'F');
/*
Here 6 is starting index and 1 is no. of array elements to remove and
final argument 'F' is the new character to be inserted.
*/
var result = arr.join(""); // "White Fog"
One-liner using String.replace with callback (no emoji support):
// 0 - index to replace, 'f' - replacement string
'dog'.replace(/./g, (c, i) => i == 0? 'f': c)
// "fog"
Explained:
//String.replace will call the callback on each pattern match
//in this case - each character
'dog'.replace(/./g, function (character, index) {
if (index == 0) //we want to replace the first character
return 'f'
return character //leaving other characters the same
})
Generalizing Afanasii Kurakin's answer, we have:
function replaceAt(str, index, ch) {
return str.replace(/./g, (c, i) => i == index ? ch : c);
}
let str = 'Hello World';
str = replaceAt(str, 1, 'u');
console.log(str); // Hullo World
Let's expand and explain both the regular expression and the replacer function:
function replaceAt(str, index, newChar) {
function replacer(origChar, strIndex) {
if (strIndex === index)
return newChar;
else
return origChar;
}
return str.replace(/./g, replacer);
}
let str = 'Hello World';
str = replaceAt(str, 1, 'u');
console.log(str); // Hullo World
The regular expression . matches exactly one character. The g makes it match every character in a for loop. The replacer function is called given both the original character and the index of where that character is in the string. We make a simple if statement to determine if we're going to return either origChar or newChar.
var str = "hello world";
console.log(str);
var arr = [...str];
arr[0] = "H";
str = arr.join("");
console.log(str);
This works similar to Array.splice:
String.prototype.splice = function (i, j, str) {
return this.substr(0, i) + str + this.substr(j, this.length);
};
You could try
var strArr = str.split("");
strArr[0] = 'h';
str = strArr.join("");
this is easily achievable with RegExp!
const str = 'Hello RegEx!';
const index = 11;
const replaceWith = 'p';
//'Hello RegEx!'.replace(/^(.{11})(.)/, `$1p`);
str.replace(new RegExp(`^(.{${ index }})(.)`), `$1${ replaceWith }`);
//< "Hello RegExp"
Using the spread syntax, you may convert the string to an array, assign the character at the given position, and convert back to a string:
const str = "hello world";
function replaceAt(s, i, c) {
const arr = [...s]; // Convert string to array
arr[i] = c; // Set char c at pos i
return arr.join(''); // Back to string
}
// prints "hallo world"
console.log(replaceAt(str, 1, 'a'));
You could try
var strArr = str.split("");
strArr[0] = 'h';
str = strArr.join("");
Check out this function for printing steps
steps(3)
// '# '
// '## '
// '###'
function steps(n, i = 0, arr = Array(n).fill(' ').join('')) {
if (i === n) {
return;
}
str = arr.split('');
str[i] = '#';
str = str.join('');
console.log(str);
steps(n, (i = i + 1), str);
}
#CemKalyoncu: Thanks for the great answer!
I also adapted it slightly to make it more like the Array.splice method (and took #Ates' note into consideration):
spliceString=function(string, index, numToDelete, char) {
return string.substr(0, index) + char + string.substr(index+numToDelete);
}
var myString="hello world!";
spliceString(myString,myString.lastIndexOf('l'),2,'mhole'); // "hello wormhole!"
If you want to replace characters in string, you should create mutable strings. These are essentially character arrays. You could create a factory:
function MutableString(str) {
var result = str.split("");
result.toString = function() {
return this.join("");
}
return result;
}
Then you can access the characters and the whole array converts to string when used as string:
var x = MutableString("Hello");
x[0] = "B"; // yes, we can alter the character
x.push("!"); // good performance: no new string is created
var y = "Hi, "+x; // converted to string: "Hi, Bello!"
You can extend the string type to include the inset method:
String.prototype.append = function (index,value) {
return this.slice(0,index) + value + this.slice(index);
};
var s = "New string";
alert(s.append(4,"complete "));
Then you can call the function:
You can concatenate using sub-string function at first select text before targeted index and after targeted index then concatenate with your potential char or string. This one is better
const myString = "Hello world";
const index = 3;
const stringBeforeIndex = myString.substring(0, index);
const stringAfterIndex = myString.substring(index + 1);
const replaceChar = "X";
myString = stringBeforeIndex + replaceChar + stringAfterIndex;
console.log("New string - ", myString)
or
const myString = "Hello world";
let index = 3;
myString = myString.substring(0, index) + "X" + myString.substring(index + 1);
I did a function that does something similar to what you ask, it checks if a character in string is in an array of not allowed characters if it is it replaces it with ''
var validate = function(value){
var notAllowed = [";","_",">","<","'","%","$","&","/","|",":","=","*"];
for(var i=0; i<value.length; i++){
if(notAllowed.indexOf(value.charAt(i)) > -1){
value = value.replace(value.charAt(i), "");
value = validate(value);
}
}
return value;
}
Here is a version I came up with if you want to style words or individual characters at their index in react/javascript.
replaceAt( yourArrayOfIndexes, yourString/orArrayOfStrings )
Working example: https://codesandbox.io/s/ov7zxp9mjq
function replaceAt(indexArray, [...string]) {
const replaceValue = i => string[i] = <b>{string[i]}</b>;
indexArray.forEach(replaceValue);
return string;
}
And here is another alternate method
function replaceAt(indexArray, [...string]) {
const startTag = '<b>';
const endTag = '</b>';
const tagLetter = i => string.splice(i, 1, startTag + string[i] + endTag);
indexArray.forEach(tagLetter);
return string.join('');
}
And another...
function replaceAt(indexArray, [...string]) {
for (let i = 0; i < indexArray.length; i++) {
string = Object.assign(string, {
[indexArray[i]]: <b>{string[indexArray[i]]}</b>
});
}
return string;
}
Here is my solution using the ternary and map operator. More readable, maintainable end easier to understand if you ask me.
It is more into es6 and best practices.
function replaceAt() {
const replaceAt = document.getElementById('replaceAt').value;
const str = 'ThisIsATestStringToReplaceCharAtSomePosition';
const newStr = Array.from(str).map((character, charIndex) => charIndex === (replaceAt - 1) ? '' : character).join('');
console.log(`New string: ${newStr}`);
}
<input type="number" id="replaceAt" min="1" max="44" oninput="replaceAt()"/>
My safe approach with negative indexes
/**
* #param {string} str
* #param {number} index
* #param {string} replacement
* #returns {string}
*/
static replaceAt (str, index, replacement)
{
if (index < 0) index = str.length + index
if (index < 0 || index >= str.length) throw new Error(`Index (${index}) out of bounds "${str}"`)
return str.substring(0, index) + replacement + str.substring(index + 1)
}
Use it like that:
replaceAt('my string', -1, 'G') // 'my strinG'
replaceAt('my string', 2, 'yy') // 'myyystring'
replaceAt('my string', 22, 'yy') // Uncaught Error: Index (22) out of bounds "my string"
Lets say you want to replace Kth index (0-based index) with 'Z'.
You could use Regex to do this.
var re = var re = new RegExp("((.){" + K + "})((.){1})")
str.replace(re, "$1A$`");
You can use the following function to replace Character or String at a particular position of a String. To replace all the following match cases use String.prototype.replaceAllMatches() function.
String.prototype.replaceMatch = function(matchkey, replaceStr, matchIndex) {
var retStr = this, repeatedIndex = 0;
for (var x = 0; (matchkey != null) && (retStr.indexOf(matchkey) > -1); x++) {
if (repeatedIndex == 0 && x == 0) {
repeatedIndex = retStr.indexOf(matchkey);
} else { // matchIndex > 0
repeatedIndex = retStr.indexOf(matchkey, repeatedIndex + 1);
}
if (x == matchIndex) {
retStr = retStr.substring(0, repeatedIndex) + replaceStr + retStr.substring(repeatedIndex + (matchkey.length));
matchkey = null; // To break the loop.
}
}
return retStr;
};
Test:
var str = "yash yas $dfdas.**";
console.log('Index Matched replace : ', str.replaceMatch('as', '*', 2) );
console.log('Index Matched replace : ', str.replaceMatch('y', '~', 1) );
Output:
Index Matched replace : yash yas $dfd*.**
Index Matched replace : yash ~as $dfdas.**
I se this to make a string proper case, that is, the first letter is Upper Case and all the rest are lower case:
function toProperCase(someString){
return someString.charAt(0).toUpperCase().concat(someString.toLowerCase().substring(1,someString.length));
};
This first thing done is to ensure ALL the string is lower case - someString.toLowerCase()
then it converts the very first character to upper case -someString.charAt(0).toUpperCase()
then it takes a substring of the remaining string less the first character -someString.toLowerCase().substring(1,someString.length))
then it concatenates the two and returns the new string -someString.charAt(0).toUpperCase().concat(someString.toLowerCase().substring(1,someString.length))
New parameters could be added for the replacement character index and the replacement character, then two substrings formed and the indexed character replaced then concatenated in much the same way.
The solution does not work for negative index so I add a patch to it.
String.prototype.replaceAt=function(index, character) {
if(index>-1) return this.substr(0, index) + character + this.substr(index+character.length);
else return this.substr(0, this.length+index) + character + this.substr(index+character.length);
}
"hello world".replace(/(.{3})./, "$1h")
// 'helho world'
The methods on here are complicated.
I would do it this way:
var myString = "this is my string";
myString = myString.replace(myString.charAt(number goes here), "insert replacement here");
This is as simple as it gets.