Replicating string.format() of C# in JavaScript without numeric placeholders

Question

String.Format method of C# allows you to keep "Replaces one or more format items in a specified string with the string representation of a specified object."

string text = "select {0},{1},{2} from {3} where {4};"
var result = String.Format(text, "col1","col2","col3","table","col1 > 10");

after this result would look like

select col1,col2, col3 from table where col1 > 10;

I am also utilizing similar function in JavaScript which looks like this.

this.FormatString = function() {
    var s = arguments[0];
    for (var i = 0; i < arguments.length - 1; i++) {
        var reg = new RegExp("\\{" + i + "\\}", "gm");
        s = s.replace(reg, arguments[i + 1]);
    }
    return s;
};

My question is there any way to use logical name as placeholders instead of using replying on numeric placeholders.

So instead of using

string text = "select {0},{1},{2} from {3} where {4};"

I want to use

string text = "select {Column List} from {TableName} where {Where Clause};"

I know using logical names as placeholders is not generic as compared to having numeric placeholder which allows user to pass N numbers of parameters (or create N numbers of placeholders).

I am looking for solution by using JavaScript or any JavaScript based library.

FYI: ECMAScript 6 has built in template strings: tc39wiki.calculist.org/es6/template-strings. If you use TypeScript on top of your JavaScript, you can already use this feature. — Matthijs Wessels
– Matthijs Wessels, Commented Feb 5, 2015 at 10:14

LukeH · Accepted Answer · 2014-04-02 10:10:05Z

3

I'm not sure exactly what you're looking for. Maybe something like this?

var text = 'select {ColumnList} from {TableName} where {WhereClause}';
var values = {
    ColumnList:  'col1, col2, col3',
    TableName:   'table',
    WhereClause: 'col1 > 10'
};

var formatted = formatString(text, values);
// formatted now contains 'select col1, col2, col3 from table where col1 > 10'


function formatString (src, obj) {
    for (var key in obj) {
        if (obj.hasOwnProperty(key)) {
            var rx = new RegExp('\\{' + key + '\\}', 'gm');
            src = src.replace(rx, obj[key]);
        }
    }
    return src;
}

answered Apr 2, 2014 at 10:10

LukeH

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