Suppose I have string variable such as:
var a = "xxxxxxxxhelloxxxxxxxx";
or:
var a = "xxxxhelloxxxx";
I want to insert "world" after "hello".
I can't use substr() because the position is not known ahead of time. How can I do this in JavaScript or jQuery?
var a = "xxxxhelloxxxxhelloxxxx";
a = a.replace(/hello/g,"hello world"); // if you want all the "hello"'s in the string to be replaced
document.getElementById("regex").textContent = a;
a = "xxxxhelloxxxxhelloxxxx";
a = a.replace("hello","hello world"); // if you want only the first occurrence of "hello" to be replaced
document.getElementById("string").textContent = a;<p>With regex: <strong id="regex"></strong></p>
<p>With string: <strong id="string"></strong></p>
This will replace the first occurrence
a = a.replace("hello", "helloworld");
If you need to replace all of the occurrences, you'll need a regular expression. (The g flag at the end means "global", so it will find all occurences.)
a = a.replace(/hello/g, "helloworld");
This will replace the first occurance:
a = a.replace("hello", "hello world");
If you need to replace all occurances, you use a regular expression for the match, and use the global (g) flag:
a = a.replace(/hello/g, "hello world");
Here are two ways to avoid repeating the pattern:
a_new = a.replace(/hello/, '$& world'); // "xxxxxxxxhello worldxxxxxxxx"
$& represents the substring that matched the whole pattern. It is a special code for use in the replacement string.
a_new = a.replace(/hello/, function (match) {
return match + ' world';
});
A replacer function is passed the same substring that matched the whole pattern.
var find = "hello";
var a = "xxxxxxxxxxxxxhelloxxxxxxxxxxxxxxxx";
var i = a.indexOf(find);
var result = a.substr(0, i+find.length) + "world" + a.substr(i+find.length);
alert(result); //xxxxxxxxxxxxxhelloworldxxxxxxxxxxxxxxxx
Maybe.
You can use replace, would be much easier than indexOf
var newstring = a.replace("hello", "hello world");
