Performance comparison between static and dynamic interpolation techniques in Angular.js

Question

Performance comparison between static and dynamic interpolation techniques in Angular.js

Could you explain the discrepancies between:

A: {{ variable | filter }}

and

B: {{ 'static string' | filter }}

I have a few questions regarding this:

Are both considered interpolations or just A?
Does A utilize $interpolate, while B utilizes $parse? (based on another insightful discussion found on Stack Overflow)
How do these two methods differ in terms of performance? With A, every time the value of variable changes, the template gets updated as it listens for changes. If there are multiple interpolations like A, could this lead to performance issues due to extensive model listening? Does B handle this differently? Specifically, I am considering implementing Angular Translate, which makes use of the translate filter. It involves a global variable that stores the current language used in the interface; when the language changes, all B interpolations with the translate filter update. But how does this mechanism work internally? What is being monitored and by whom? Is there only one listener for changes in the language variable (stored in Angular config) that facilitates updating multiple i18n-labels on language alterations? Or are there several listeners involved? If I were to include 500
```
{{ 'static string' | translate }}
```
interpolations, would this potentially impact application speed due to excessive listening?

If any of my assumptions are incorrect, kindly advise.

javascript angularjs performance templates string-interpolation

Answer 1

Answer №1

Interpolations are utilized in both cases. When the symbols {{ and }} are present (unless modified), the enclosed content will undergo interpolation.

As previously mentioned, both instances of A and B make use of the $interpolate service. This service employs the $parse service, resulting in both A and B essentially utilizing both services.

The following strings are passed from $interpolate to $parse:

In scenario A: variable | uppercase

In scenario B: 'static string' | filter

The number of watchers added for these scenarios is identical, as it pertains to monitoring the combined nodeValue of the node.

For instance, there is also no discrepancy in the number of watchers added between the following cases:

<div>{{one}}</div>

<div>{{one}} {{two}}</div>

The distinction in performance between scenarios A and

B</code lies in the functions used to retrieve the left-hand side of the expression.</p>

<p>In situation <code>A

, it essentially involves:

function (locals, scope) {
  return ((locals && locals.hasOwnProperty('variable')) ? locals : scope).variable;
}

While in scenario B (where string is stored in a closure with the value being static string):

function() { return string; }

The difference in execution time between the two should not be significant (unless dealing with an excessive amount of interpolations).

Filters should typically be kept uncomplicated as they can be executed multiple times.

In AngularJS 1.3.0-rc.2, filters were made stateless by default, leading to a notable enhancement in performance.

Consider this example:

<div>{{ variable | uppercase }}</div>

During the digest loop iteration, upon identifying the value of variable, the filter is applied. If the subsequent digest loop iteration reveals that the value of variable remains unchanged, the stateless nature of filters allows them to utilize the cached result from the prior application rather than recomputing.

To delve further into this topic, you can refer to this link.

However, filters may deviate from this standard and become stateful, such as seen with the translate filter in Angular Translate. This adjustment is necessary due to the dynamic language changes possible during runtime, where the translation of hello varies across different languages.

Regarding the performance implications of Angular Translate, I plan to investigate further and provide updates to my answer tomorrow.

Answer 2

Interpolations are utilized in both cases. When the symbols {{ and }} are present (unless modified), the enclosed content will undergo interpolation.

As previously mentioned, both instances of A and B make use of the $interpolate service. This service employs the $parse service, resulting in both A and B essentially utilizing both services.

The following strings are passed from $interpolate to $parse:

In scenario A: variable | uppercase

In scenario B: 'static string' | filter

The number of watchers added for these scenarios is identical, as it pertains to monitoring the combined nodeValue of the node.

For instance, there is also no discrepancy in the number of watchers added between the following cases:

<div>{{one}}</div>

<div>{{one}} {{two}}</div>

The distinction in performance between scenarios A and

B</code lies in the functions used to retrieve the left-hand side of the expression.</p>

<p>In situation <code>A

, it essentially involves:

function (locals, scope) {
  return ((locals && locals.hasOwnProperty('variable')) ? locals : scope).variable;
}

While in scenario B (where string is stored in a closure with the value being static string):

function() { return string; }

The difference in execution time between the two should not be significant (unless dealing with an excessive amount of interpolations).

Filters should typically be kept uncomplicated as they can be executed multiple times.

In AngularJS 1.3.0-rc.2, filters were made stateless by default, leading to a notable enhancement in performance.

Consider this example:

<div>{{ variable | uppercase }}</div>

During the digest loop iteration, upon identifying the value of variable, the filter is applied. If the subsequent digest loop iteration reveals that the value of variable remains unchanged, the stateless nature of filters allows them to utilize the cached result from the prior application rather than recomputing.

To delve further into this topic, you can refer to this link.

However, filters may deviate from this standard and become stateful, such as seen with the translate filter in Angular Translate. This adjustment is necessary due to the dynamic language changes possible during runtime, where the translation of hello varies across different languages.

Regarding the performance implications of Angular Translate, I plan to investigate further and provide updates to my answer tomorrow.

Performance comparison between static and dynamic interpolation techniques in Angular.js

Answer №1

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