So, title says most of it, and I'll give an example:
var foo = ['one', 'two', 'three'];
var bar = [
{
integer: 1,
string: 'one'
},
{
integer: 3,
string: 'three'
}
];
Now, I'm wondering how can I get the list of positive matches for each of the elements in foo against each of the string properties of all the objects in array bar.
First, make a set of all elements in foo to avoid square complexity:
var fooSet = {};
for(var i = 0; i < foo.length; i++) {
var e = foo[i];
fooSet[e] = true;
}
Then, go through bar and gather matches:
var matches = [];
for(var i = 0; i < bar.length; i++) {
var e = bar[i];
if(fooSet[e.string]) {
matches.push(e);
}
}
After this, matches array will contain the elements from bar that match the elements of foo.
Here's a live example:
fooSet makes this better than my answer that used .indexOf() (especially now that you've removed the for..in loops).
foo and bar - here's an example where foo has 8 and bar has 3 elements: jsfiddle.net/mfAc4/1 and here's an example where foo has 2 and bar has 3 elements: jsfiddle.net/mfAc4/2. Is this what you are looking for?Loop through one of the arrays checking each item against the other:
var matches = [],
i, j;
for (i=0; i < bar.length; i++)
if (-1 != (j = foo.indexOf(bar[i].string)))
matches.push(foo[j]);
// matches is ['one', 'three']
Obviously if you want matches to contain the items from bar rather than foo just change the .push() statement to matches.push(bar[i]);.
Of course the above assumes you don't care about supporting older browsers that don't do .indexOf() on arrays, or that you can use a shim.
These 2 work. Depends on how you want to use the data you can modify.
WAY ONE
//wasn't sure which one you want to utilize so I'm doing both
//storing the index of foo to refer to the array
var wayOneArrayFOO= Array();
//storing the index of bar to refer to the array
var wayOneArrayBAR= Array();
var fooLength = foo.length;
var barLength = bar.length;
/*THE MAGIC*/
//loop through foo
for(i=0;i<fooLength;i++){
//while your looping through foo loop through bar
for(j=0;j<barLength;j++){
if(foo[i]==bar[j].string){
wayOneArrayFOO.push(i);
wayOneArrayBAR.push(j);
}
}
}
WAY TWO
//storing the value of foo
var wayTwoArrayFOO= Array();
//storing the value of bar
var wayTwoArrayBAR= Array();
/*THE MAGIC*/
//loop through foo
for(i=0;i<fooLength;i++){
//while your looping through foo loop through bar
for(j=0;j<barLength;j++){
if(foo[i]==bar[j].string){
wayTwoArrayFOO.push(foo[i]);
wayTwoArrayBAR.push(bar[j]);
}
}
}
This:
// foo & bar defined here
// put all the keys from the foo array to match on in a dictionary (object)
var matchSet = {};
for (var item in foo)
{
var val = foo[item];
matchSet[val] = 1;
}
// loop through the items in the bar array and see if the string prop is in the matchSet
// if so, add it to the matches array
var matches = [];
for (var i=0; i < bar.length; i++)
{
var item = bar[i];
if (matchSet.hasOwnProperty(item['string']))
{
matches.push(item['string']);
}
}
// output the matches (using node to output to console)
for (var i in matches)
{
console.log(matches[i]);
}
Outputs:
match: one
match: three
NOTE: using node to run interactively
