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util: speed up formatting of large arrays/objects 

Don't .indexOf() into the keys array. V8 is smart but not so smart that it
knows how to turn the linear scan into a O(1) lookup.

Fixes #3562.
pull/24503/head
Ben Noordhuis 2012-06-27 19:15:28 +02:00
parent be3afd0bec
commit 6531f187d8
1 changed files with 18 additions and 3 deletions
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21
lib/util.js
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@ -175,6 +175,17 @@ function stylizeNoColor(str, styleType) {
}
function arrayToHash(array) {
var hash = {};
array.forEach(function(val, idx) {
hash[val] = true;
});
return hash;
}
function formatValue(ctx, value, recurseTimes) {
// Provide a hook for user-specified inspect functions.
// Check that value is an object with an inspect function on it
@ -193,8 +204,12 @@ function formatValue(ctx, value, recurseTimes) {
}
// Look up the keys of the object.
var visibleKeys = Object.keys(value);
var keys = ctx.showHidden ? Object.getOwnPropertyNames(value) : visibleKeys;
var keys = Object.keys(value);
var visibleKeys = arrayToHash(keys);
if (ctx.showHidden) {
keys = Object.getOwnPropertyNames(value);
}
// Some type of object without properties can be shortcutted.
if (keys.length === 0) {
@ -334,7 +349,7 @@ function formatProperty(ctx, value, recurseTimes, visibleKeys, key, array) {
str = ctx.stylize('[Setter]', 'special');
}
}
if (visibleKeys.indexOf(key) < 0) {
if (!visibleKeys.hasOwnProperty(key)) {
name = '[' + key + ']';
}
if (!str) {