JavaScript string manipulation

1. Replacing substrings

Replace (search,replacement)
Find the substring that satisfies the criteria search, replace with replacement

Note: By default, only the first substring found is replaced, and if you want to replace all, you need to write:

 x.replace (/a/g,  o    var  regs = new  RegExp ( a   ", "  g   "; X.replace (regs,   " o  ); 

<script>
function P (s) {
document.write (s);
document.write ("<br>");
}

var x = new String ("Hello JavaScript");
P (' This is the original string: ' +x ');
var y = x.replace ("A", "O");
P (' Replace only the first A: ' +y);
var regs = new RegExp ("A", "G");
var z = x.replace (regs, "O");
P (' Replace all A: ' +z);

</script>

2. Intercept a substring

SUBSTRING intercept a substring
Note: The second parameter, cannot be taken

Cases:

< script >    var x = new String("Hello JavaScript");   document.write( ‘字符串x的值: ‘+x); document.write(‘< br >‘); document.write(‘x.substring (0,3) 获取位0到3的字符串： ‘+x.substring (0,3) ); document.write(‘< br >‘); document.write(‘左闭右开，取得到0，去不到3‘); </ script >3. Returns the character at the specified position

CharAt returns the character at the specified position
charCodeAt returns the Unicode code corresponding to the character at the specified position

< script >   var y = new String("Hello JavaScrpt"); document.write("字符串y的值:"+y); document.write("< br >"); document.write(‘通过 charAt(0)获取位置0的字符串： ‘+y.charAt(0)); //返回H document.write("< br >"); document.write(‘通过 charCodeAt(0)获取位置0的字符的 Unicode码 ：‘+y.charCodeAt(0)); //返回H对应的Unicode码 72 </ script >

JavaScript string manipulation