replace characters in a string using an associative array mapping

Question

I have an associative array/object such at this:

mymap = {'e':'f', 'l':'g'};

And I want to replace all matching characters in a string using the above as a simple cypher, but only replacing existing characters. As an example,

input = "hello world";
output = input.map(mymap); //how can I do this?
//output is "hfggo worgd"

Balancing performance (for large input) and code size are of interest.

My application is replacing unicode characters with latex strings using this map, but I'm happy to stick with the more general question.

jozxyqk · Accepted Answer · 2015-03-10 11:17:37Z

2

The following works:

mymap = {'e':'f', 'l':'g'};

var replacechars = function(c){
    return mymap[c] || c;
};

input = "hello world";
output = input.split('').map(replacechars).join('');

although having to split and then join the input seems quite round-about, particularly if this is applied to a wall of text.

answered Mar 10, 2015 at 11:17

jozxyqk

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Joe Fitter · Accepted Answer · 2015-03-10 11:24:17Z

1

Another way would be loop over the object properties and use regex for each replacement:

var input = 'hello world';
var output = '';

for (var prop in mymap) {
    if (mymap.hasOwnProperty(prop)) {
        var re = new RegExp(prop, 'g');
        output = input.replace(re, mymap[prop]);
    }
}

answered Mar 10, 2015 at 11:24

Joe Fitter

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