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startsWith() : Check String Prefix

Check if a string starts with a specified prefix.

On this page

Signature

startsWith(str, prefix)

Parameters

Parameter Type Required Description
str String Yes The string to check
prefix String Yes The prefix to look for

Returns

Type: Boolean

true if the string starts with the prefix, false otherwise.

Examples

Protocol Detection

{{#if startsWith(model.url, 'https://')}}
  <span class="secure">🔒 Secure</span>
{{else}}
  <span class="insecure">âš  Not Secure</span>
{{/if}}

Data:

doc.Params["model"] = new {
    url = "https://example.com"
};

Output:

<span class="secure">🔒 Secure</span>

File Type Detection

{{#each model.files}}
  {{#if startsWith(this.name, 'report_')}}
    <div class="file-report">
      <span class="icon">📄</span> {{this.name}}
    </div>
  {{/if}}
{{/each}}

Data:

doc.Params["model"] = new {
    files = new[] {
        new { name = "report_2024.pdf" },
        new { name = "data.csv" },
        new { name = "report_summary.xlsx" }
    }
};

Output:

<div class="file-report">
  <span class="icon">📄</span> report_2024.pdf
</div>
<div class="file-report">
  <span class="icon">📄</span> report_summary.xlsx
</div>

Prefix-Based Filtering

{{#each model.codes}}
  {{#if startsWith(this, 'PRO-')}}
    <span class="code-professional">{{this}}</span>
  {{else if startsWith(this, 'STD-')}}
    <span class="code-standard">{{this}}</span>
  {{/if}}
{{/each}}

Phone Number Validation

{{#if startsWith(model.phone, '+1')}}
  <p>US/Canada: {{model.phone}}</p>
{{else if startsWith(model.phone, '+44')}}
  <p>UK: {{model.phone}}</p>
{{else}}
  <p>International: {{model.phone}}</p>
{{/if}}

Data:

doc.Params["model"] = new {
    phone = "+1-555-123-4567"
};

Output:

<p>US/Canada: +1-555-123-4567</p>

Notes

  • Case-sensitive by default
  • Returns false if prefix is not found at beginning
  • Empty prefix returns true
  • For case-insensitive check, use with toLower(): startsWith(toLower(str), toLower(prefix))
  • For suffix checking, use endsWith()
  • For substring anywhere, use contains()

See Also