vowel replacer leet - stage 2

JavaScript

var word = '';
var output_word = '';
var increment = 0;

word = prompt('Type something and I will replace the vowels');

for (increment = 0; increment < word.length; increment++) {

	if (word[increment] == 'a') {
   	output_word = output_word + '4';
  }
  else if(word[increment] == 'e') {
		output_word = output_word + '3';
  }
  else if(word[increment] == 'i') {
    output_word = output_word + '1';
  }
  else if(word[increment] == 'o') {
		output_word = output_word + '0';    
  }
  else if(word[increment] == 'u') {
  	output_word = output_word + '|_|';    
  }
  else {
  	output_word = output_word + word[increment];
  }
  
}

document.write(output_word);