I have an array of values to which I want to add some prefix:
var arr = ["1.jpg", "2.jpg", "some.jpg"];
Adding the prefix images/ should result in this:
newArr = ["images/1.jpg", "images/2.jpg", "images/some.jpg"];
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6 Answers
Array.prototype.map is a great tool for this kind of things:
arr.map(function(el) {
return 'images/' + el;
})
In ES2015+:
arr.map(el => 'images/' + el)
Comments
const newArr = arr.map(i => 'images/' + i)
Same thing but without using ES6 syntax:
var arr = arr.map(function (i){
return 'images/' + i;
})
Comments
For browser compatibility and without loop:
var pre = 'images/';
var arr = ['1.jpg', '2.jpg', 'some.jpg'];
var newArr = (pre + arr.join(';' + pre)).split(';');
1 Comment
DarthCadeus
What if the contents of the file name contains ";", as in "me;mycat.jpg"
You can simply do this with a simple loop:
var arr = ["1.jpg","2.jpg","some.jpg"],
newArr = [];
for(var i = 0; i<arr.length; i++){
newArr[i] = 'images/' + arr[i];
}
Comments
You can use Jquery library
var newArr = jQuery.map( arr, function( n, i ) {
return ( "images/"+n );
});
4 Comments
George
Who said anything about jQuery?
DannyTheDev
I love how the jQuery version is longer than the native version - and slower
kemenov
Native version is not work in IE 8. The question can be opened from the different parties, native approach has been proposed in other answers.
George
There are other substitutes for
Array.map() that don't involve including an entire library. Johnroe Paulo Cañamaque's answer for example.You can use Rest parameters with Array.prototype.map().
function addPathPrefix(prefix, ...filenames) {
return filenames.map((filename) => `${prefix}${filename}`)
}
const arr = ["1.jpg", "2.jpg", "some.jpg"]
console.log(addPathPrefix("images/", ...arr))