Replace multiple strings at once

Is there an easy equivalent to this in JavaScript?

$find = array("<", ">", "\n");
$replace = array("&lt;", "&gt;", "<br/>");

$textarea = str_replace($find, $replace, $textarea); 

This is using PHP's str_replace, which allows you to use an array of words to look for and replace. Can I do something like this using JavaScript / jQuery?

...
var textarea = $(this).val();

// string replace here
	
$("#output").html(textarea);
...

You could extend the String object with your own function that does what you need (useful if there's ever missing functionality):

String.prototype.replaceArray = function(find, replace) {
  var replaceString = this;
  for (var i = 0; i < find.length; i++) {
    replaceString = replaceString.replace(find[i], replace[i]);
  }
  return replaceString;
};

For global replace you could use regex:

String.prototype.replaceArray = function(find, replace) {
  var replaceString = this;
  var regex; 
  for (var i = 0; i < find.length; i++) {
    regex = new RegExp(find[i], "g");
    replaceString = replaceString.replace(regex, replace[i]);
  }
  return replaceString;
};

To use the function it'd be similar to your PHP example:

var textarea = $(this).val();
var find = ["<", ">", "\n"];
var replace = ["&lt;", "&gt;", "<br/>"];
textarea = textarea.replaceArray(find, replace);

Common Mistake

Nearly all answers on this page use cumulative replacement and thus suffer the same flaw where replacement strings are themselves subject to replacement. Here are a couple examples where this pattern fails (h/t @KurokiKaze @derekdreery):

function replaceCumulative(str, find, replace) {
  for (var i = 0; i < find.length; i++)
    str = str.replace(new RegExp(find[i],"g"), replace[i]);
  return str;
};

// Fails in some cases:
console.log( replaceCumulative( "tar pit", ['tar','pit'], ['capitol','house'] ) );
console.log( replaceCumulative( "you & me", ['you','me'], ['me','you'] ) );

Solution

function replaceBulk( str, findArray, replaceArray ){
  var i, regex = [], map = {}; 
  for( i=0; i<findArray.length; i++ ){ 
    regex.push( findArray[i].replace(/([-[\]{}()*+?.\\^$|#,])/g,'\\$1') );
    map[findArray[i]] = replaceArray[i]; 
  }
  regex = regex.join('|');
  str = str.replace( new RegExp( regex, 'g' ), function(matched){
    return map[matched];
  });
  return str;
}

// Test:
console.log( replaceBulk( "tar pit", ['tar','pit'], ['capitol','house'] ) );
console.log( replaceBulk( "you & me", ['you','me'], ['me','you'] ) );

Note:

This is a more compatible variation of @elchininet's solution, which uses map() and Array.indexOf() and thus won't work in IE8 and older.

@elchininet's implementation holds truer to PHP's str_replace(), because it also allows strings as find/replace parameters, and will use the first find array match if there are duplicates (my version will use the last). I didn't accept strings in this implementation because that case is already handled by JS's built-in String.replace().

text = text.replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/\n/g, '<br/>');

You could use the replace method of the String object with a function in the second parameter:

First Method (using a find and replace Object)

var findreplace = {"<" : "&lt;", ">" : "&gt;", "\n" : "<br/>"};

textarea = textarea.replace(new RegExp("(" + Object.keys(findreplace).map(function(i){return i.replace(/[.?*+^$[\]\\(){}|-]/g, "\\$&")}).join("|") + ")", "g"), function(s){ return findreplace[s]});

jsfiddle

Second method (using two arrays, find and replace)

var find = ["<", ">", "\n"];
var replace = ["&lt;", "&gt;", "<br/>"];

textarea = textarea.replace(new RegExp("(" + find.map(function(i){return i.replace(/[.?*+^$[\]\\(){}|-]/g, "\\$&")}).join("|") + ")", "g"), function(s){ return replace[find.indexOf(s)]});

jsfiddle

Desired function:

function str_replace($f, $r, $s){
   return $s.replace(new RegExp("(" + $f.map(function(i){return i.replace(/[.?*+^$[\]\\(){}|-]/g, "\\$&")}).join("|") + ")", "g"), function(s){ return $r[$f.indexOf(s)]});
}

$textarea = str_replace($find, $replace, $textarea);

EDIT

This function admits a String or an Array as parameters:

function str_replace($f, $r, $s){
    return $s.replace(new RegExp("(" + (typeof($f) === "string" ? $f.replace(/[.?*+^$[\]\\(){}|-]/g, "\\$&") : $f.map(function(i){return i.replace(/[.?*+^$[\]\\(){}|-]/g, "\\$&")}).join("|")) + ")", "g"), typeof($r) === "string" ? $r : typeof($f) === "string" ? $r[0] : function(i){ return $r[$f.indexOf(i)]});
}

A more visual approach:

String.prototype.htmlProtect = function() {
  var replace_map;

  replace_map = {
    '\n': '<br />',
    '<': '&lt;',
    '>': '&gt;'
  };

  return this.replace(/[<>\n]/g, function(match) { // be sure to add every char in the pattern
    return replace_map[match];
  });
};

and this is how you call it:

var myString = "<b>tell me a story, \n<i>bro'</i>";
var myNewString = myString.htmlProtect();

// &lt;b&gt;tell me a story, <br />&lt;i&gt;bro'&lt;/i&gt;

The top answer is equivalent to doing:

let text = find.reduce((acc, item, i) => {
  const regex = new RegExp(item, "g");
  return acc.replace(regex, replace[i]);
}, textarea);

Given this:

var textarea = $(this).val();
var find = ["<", ">", "\n"];
var replace = ["&lt;", "&gt;", "<br/>"];

In this case, no imperative programming is going on.

Using ES6: There are many ways to search for strings and replace in JavaScript. One of them is as follow

const findFor = ['<', '>', '\n'];

const replaceWith = ['&lt;', '&gt;', '<br/>'];

const originalString = '<strong>Hello World</strong> \n Let\'s code';

let modifiedString = originalString;

findFor.forEach( (tag, i) => modifiedString = modifiedString.replace(new RegExp(tag, "g"), replaceWith[i]) )

console.log('Original String: ', originalString);
console.log('Modified String: ', modifiedString);

A simple forEach loop solves this quite well:

let text = 'the red apple and the green ball';
const toStrip = ['red', 'green'];
toStrip.forEach(x => {
   text = text.replace(x, '');
});

console.log(text);
// logs -> the apple and the ball

You might want to look into a JS library called phpJS.

It allows you to use the str_replace function similarly to how you would use it in PHP. There are also plenty more php functions "ported" over to JavaScript.

http://phpjs.org/functions/str_replace:527

String.prototype.replaceArray = function (find, replace) {
    var replaceString = this;
    for (var i = 0; i < find.length; i++) {
        // global replacement
        var pos = replaceString.indexOf(find[i]);
        while (pos > -1) {
            replaceString = replaceString.replace(find[i], replace[i]);
            pos = replaceString.indexOf(find[i]);
        }
    }
    return replaceString;
};

var textT = "Hello world,,,,, hello people.....";
var find = [".",","];
var replace = ['2', '5'];
textT = textT.replaceArray(find, replace);
// result: Hello world55555 hello people22222

const items = {
  '<': '&lt;',
  '>': '&gt;',
  '\n': '<br/>',
}

const re = new RegExp('[' + Object.keys(items).join('') + ']', 'g')

const input = '<foo>\n<bar>'

const output = input.replaceAll(re, key => items[key])

console.log(output)

There is no way to do this in one method call, you'll have to either chain calls together, or write a function that manually does what you need.

var s = "<>\n";
s = s.replace("<", "&lt;");
s = s.replace(">", "&gt;");
s = s.replace("\n", "<br/>");

For the tags, you should be able to just set the content with .text() instead of .html().

Example: http://jsfiddle.net/Phf4u/1/

var textarea = $('textarea').val().replace(/<br\s?\/?>/, '\n');

$("#output").text(textarea);

...or if you just wanted to remove the <br> elements, you could get rid of the .replace(), and temporarily make them DOM elements.

Example: http://jsfiddle.net/Phf4u/2/

var textarea = $('textarea').val();

textarea = $('<div>').html(textarea).find('br').remove().end().html();

$("#output").text(textarea);

A version with an object as a parameter:

String.prototype.strtr = function (replace) {
    keys = Object.keys(replace);
    result = this;
    for (i = 0; i < keys.length; i++) {
        result = result.replace(keys[i], replace[keys[i]]);
    }
    return result;
}

function htmlspecialchars(str) {
    return String(str).strtr({">": "&gt;", "<": "&lt;", "\n": "<br/>"});
}

// usage
text = "<span>spam</span>";
htmlspecialchars(text);

jquery have a solution for that.

var htmlString = $( element).html(); $( element ).text( htmlString );

view here: https://api.jquery.com/html/

wrap all this in a function, you can pass both an array and a string

function str_replace(search,replace,subject) {
if(!Array.isArray(search)){
    subject = subject.replace(new RegExp(search, "g"), replace)
}
else{
    search.forEach( (tag, i) => subject = subject.replace(new RegExp(tag, "g"), replace[i]) )
}
return subject;
}

One method would be:

var text = $(this).val();
text = text.replace(/</g, "&lt;").replace(/>/g, "&gt;");
$("#output").html(text);