I've this problem with this code. This code should return "Interior decoration learning" but it keeps returning "home decoration learning", What am I doing wrong?
var forbidden = "home decor learn"; var items = [ ["decor", "decoration"], ["learn", "learning"], ["home", "interior"], ]; for(i = 0; i<items.length; i++){ if(forbidden.indexOf(items[i][0])){ forbidden = forbidden.replace(items[i][0], items[i][1]); } } document.write(forbidden); Thank you,
forbidden.indexOf(items[i][0]) returns the position of the match or -1 if there is no match. That means it is truthy when there is no match or when there is a match anywhere other that the start of the string. The only time it returns a falsy value is when it matches the very start of the string and returns 0, as is the case with "home" in your scenario.
To use indexOf as a test to see if a string contains a value you need your test to check whether it returned -1 or any other number (EG. you can use conditions like !== -1 or >= 0). In modern JavaScript engines or with a very simple SHIM you can use String.prototype.includes instead which returns a boolean and better signifies your intention.
In your case you don't really need an if statement at all. Just do the replacement and rely on the fact that replace is a no-op if it can't find the replacement pattern:
var forbidden = "home decor learn"; var items = [ ["decor", "decoration"], ["learn", "learning"], ["home", "interior"], ]; for(i = 0; i<items.length; i++){ forbidden = forbidden.replace(items[i][0], items[i][1]); } document.write(forbidden);Note: String.prototype.replace only replaces the first match when used with string or a non-global regex as the replacement pattern. That means your code will allow forbidden words, so long as the occur at least twice. A workaround for that is beyond the scope of this answer.
indexOfis-1, notfalse.