JavaScript Find and replace with variable in regular expression [duplicate]

Question

Possible Duplicate:
Regular Expression Pattern With A Variable

function function1() {
    var key = "name";
    var sample = "param.name['key'] = name; param.name[i] = 1000; param.name1[i] = name1;";
    var result = result.replace(/param.<<name>>\[(\d+)\]/g, 'parameter[prefix_$1]');
}

Expected result: parameter['prefix_key'] = name; parameter['prefix_i'] = 1000; I cant add variable key into the replace function in regular expresssion.
Please help how to construct the regular expression in replace

Felix Kling · Accepted Answer · 2012-12-28 11:49:27Z

1

You can make a regex out of a string by making a RegExp object:

var regex = new RegExp("param\\." + name + "\\[(\d+)\\]", "g")
var result = result.replace(regex, 'parameter[prefix_$1]');

edited Dec 28, 2012 at 11:49

Felix Kling

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answered Dec 28, 2012 at 11:27

Blender

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4 Comments

user1812171 Over a year ago

~ function function1() { var key = "name"; var sample = "param.name['key'] = name; param.name[i] = 1000; param.name1[i] = name1;"; var regex = new RegExp("param\." + name + "[(\d+)]", "g") var result = sample.replace(regex, 'parameter[prefix_$1]'); alert(result); //Expected result : parameter['prefix_key'] = name; parameter['prefix_i'] = 1000; // I cant add variable key into hte replace function in regular expresssion. }~ I have update function with your code.

Felix Kling Over a year ago

@user1812171: Blender missed some escapes... fixed. Still a duplicate though.

user1812171 Over a year ago

NOt getting proper output

Felix Kling Over a year ago

@user1812171: Since I don't know which output you get, I cannot help you much. Still, this question has been asked multiple times. Read those question, make sure you understand the basics of regular expressions and try to make it. Everything you need to know is there, you just have to put the pieces together. edit: The problem is in your original expression. \d+ only matches digits and not e.g. 'key'. Adjust your expression accordingly and it will work. If you are not very familiar with regular expression, I recommend to read regular-expressions.info.

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