In my Meteor app, I have an array of objects with the following structure
[{ type: "oldValue" }]
When I run
testArray[0].type = 'test'
console.log(testArray[0].type)
'test' is correctly printed in the console. However, when I run
testArray[0].type[1] = 'd'
console.log(testArray[0].type)
'test' is printed in the console instead of 'tdst'. The second letter wasn't changed to a d.
How can I change individual characters within a string?
JavaScript strings are immutable. You can't change characters in them, and assignment statements like the one in your question are just ignored. (Strings are not objects, if that's not clear; they're a primitive type, and though they seem like objects in some ways, they're not.)
As @Pointy pointed out, strings are immutable. If you want to change certain characters, you can work with an array of characters:
var myString = 'hello there!'
myString = myString.split('')
myString[1] = 'a'
myString = myString.join('')
console.log(myString) // 'hallo there!'
However, per your comment, you probably want to iterate through the string once, since constantly splitting and joining the string might be slow:
function replaceCharacters (str, chars, conversionFunction) {
var charBuff = []
for (var i = 0; i < str.length; i++) {
if (chars.indexOf(str[i])) {
charBuff.push(conversionFunction(str[i]))
} else {
charBuff.push(str[i])
}
}
return charBuff.join('')
}
examples:
console.log(replaceCharacters('hello', 'al', function (myChar) { return 'Z' }))
// logs 'heZZo'
// you can pass an array or a string as the second parameter
// since `.indexOf` works on both strings and arrays
and if you're working with es6:
function replaceCharacters (str, chars, conversionFunc) {
return [...str].reduce((p, c) => {
p.push(chars.indexOf(c) === -1 ? c : conversionFunc(c))
return p
}, []).join('')
}
Regarding your remark, you can write your own converter or make use of the he.js library.
Regarding the latter, you can find the library here https://github.com/mathiasbynens/he
As for writing your own converter, this will give you a head start How to convert characters to HTML entities using plain JavaScript
