javascript: how to get index of an object in an associative array?

Question

var associativeArray = [];  associativeArray['key1'] = 'value1'; associativeArray['key2'] = 'value2'; associativeArray['key3'] = 'value3'; associativeArray['key4'] = 'value4'; associativeArray['key5'] = 'value5';  var key = null; for(key in associativeArray) {     console.log("associativeArray[" + key + "]: " +  associativeArray[key]);         }  key = 'key3';  var obj = associativeArray[key];          // gives index = -1 in both cases why? var index = associativeArray.indexOf(obj);  // var index = associativeArray.indexOf(key);    console.log("obj: " + obj + ", index: " + index);    

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The above program prints index: -1, why? Is there any better way to get index of an object in an associative array without using loops?

What if I want to delete 'key3' from this array? the splice function takes first parameter as index which must be an integer.

Answer 1

indexOf only works with pure Javascript arrays, i.e. those with integer indexes. Your "array" is actually an object and should be declared as such

var associativeArray = {} 

There's no built-in indexOf for objects, but it's easy to write.

var associativeArray = {}  associativeArray['key1'] = 'value1'; associativeArray['key2'] = 'value2'; associativeArray['key3'] = 'value3'; associativeArray['key4'] = 'value4'; associativeArray['key5'] = 'value5';  var value = 'value3'; for(var key in associativeArray) {     if(associativeArray[key]==value)          console.log(key); } 

Without loops (assuming a modern browser):

foundKeys = Object.keys(associativeArray).filter(function(key) {     return associativeArray[key] == value; }) 

returns an array of keys that contain the given value.