How can I find all the elements in javaScript array that start with certain letter

问题

Is there any way to do this filtering out only items in an array that start with the letter a. ie

var fruit = 'apple, orange, apricot'.split(',');
  fruit = $.grep(fruit, function(item, index) {
  return item.indexOf('^a'); 
  });
alert(fruit);

回答1:

Three things:

• You want to split by ', ', not ','
• indexOf doesn't take a regex, but a string, so your code searches for a literal ^. Use search if you want to use regular expressions.
• indexOf (and search) do return the index where they find the sought-after term. You'll have to compare that to your expectation: == 0. Alternatively, you can use the regex test method which returns a boolean.

alert('apple, orange, apricot'.split(', ').filter(function(item, index) {
    return item.indexOf('a') == 0; 
}));
alert('apple, orange, apricot'.split(', ').filter(function(item, index) {
    return /^a/.test(item); 
}));

回答2:

You have to trim the spaces from the item before checking.

Regex to check if start with: ^a

var fruit = 'apple, orange, apricot'.split(',');
fruit = $.grep(fruit, function (item, index) {
    return item.trim().match(/^a/);
});
alert(fruit);

Other solution:

var fruits = [];
$.each(fruit, function (i, v) {
    if (v.match(/^a/)) {
        fruits.push(v);
    }
});
alert(fruits);

回答3:

You can use charAt like so :

var fruit = 'apple, orange, apricot'.split(', ');
  fruit = $.grep(fruit, function(item, index) {
  return item.charAt(0) === 'a';
});
alert(fruit);

来源：https://stackoverflow.com/questions/30210946/how-can-i-find-all-the-elements-in-javascript-array-that-start-with-certain-lett