js String prototype replace
The replace()
method returns a new string with some or all matches of a pattern replaced by a replacement. The pattern can be a string or a RegExp
, and the replacement can be a string or a function to be called for each match.
Syntax
str.replace(regexp|substr, newSubStr|function[, flags])
Parameters
regexp (pattern)
A RegExp object. The match is replaced by the return value of parameter #2.
substr (pattern)
A String that is to be replaced by newSubStr.
newSubStr (replacement)
The String that replaces the substring received from parameter #1. A number of special replacement patterns are supported; see the "Specifying a string as a parameter" section below.
function (replacement)
A function to be invoked to create the new substring (to put in place of the substring received from parameter #1). The arguments supplied to this function are described in the "Specifying a function as a parameter" section below.
Returns
A new string with some or all matches of a pattern replaced by a replacement.
Description
This method does not change the String object it is called on. It simply returns a new string.
To perform a global search and replace, either include the g switch in the regular expression or if the first parameter is a string, include g in the flags parameter.
Examples
var str = 'Twas the night before Xmas...';
var newstr = str.replace(/xmas/i, 'Christmas');
console.log(newstr); // Twas the night before Christmas...
function f2c(s1) {
// Initialize pattern.
var test = /(\d+(\.\d*)?)F\b/g;
// Use a function for the replacement.
var s2 = s1.replace(test,
function($0,$1,$2)
{
return((($1-32) * 5/9) + "C");
}
)
return s2;
}
document.write(f2c("Water freezes at 32F and boils at 212F."));
// Output: Water freezes at 0C and boils at 100C.