leftContext

Summary

Returns the characters from the beginning of a searched string up to the position before the beginning of the last match. Read-only.

Syntax

RegExp.leftContext

Examples

The following example illustrates the use of the leftContext property:

// Create the regular expression pattern.
    var re = new RegExp("d(b+)(d)","ig");
    var str = "cdbBdbsbdbdz";

    // Perform the search.
    var arr = re.exec(str);

    // Print the output.
    var s = ""
    s += "$1: " + RegExp.$1 + "<br />";
    s += "$2: " + RegExp.$2 + "<br />";
    s += "$3: " + RegExp.$3 + "<br />";
    s += "input: " + RegExp.input + "<br />";
    s += "lastMatch: " + RegExp.lastMatch + "<br />";
    s += "leftContext: " + RegExp.leftContext + "<br />";
    s += "rightContext: " + RegExp.rightContext + "<br />";
    s += "lastParen: " + RegExp.lastParen + "<br />";

    document.write(s);

Remarks

The object associated with this property is always the global RegExp object.

The initial value of the leftContext property is an empty string. The value of the leftContext property changes whenever a successful match is made.

See also

Other articles

• $1…$9 Properties (RegExp)
• index Property (RegExp)
• input Property ($_) (RegExp)
• lastIndex Property (RegExp)
• lastMatch Property ($&) (RegExp)
• lastParen Property ($+) (RegExp)
• rightContext Property ($’) (RegExp)

Attributions

• Microsoft Developer Network: Article