util: add an option for configuring break length

This commit adds a breakLength option to util.inspect(). This
option allows users to control the length at which object keys
are split across multiple lines. For backwards compatibility,
this option defaults to 60.
Fixes: #7305
PR-URL: #7499
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

Author: cjihrig

doc/api/util.md

@@ -187,6 +187,9 @@ stream.write('It works!'); // Received data: "It works!"
 `TypedArray` elements to include when formatting. Defaults to `100`. Set to
 `null` to show all array elements. Set to `0` or negative to show no array
  elements.
+*`breakLength` {number} The length at which an object's keys are split
+ across multiple lines. Set to `Infinity` to format an object as a single
+ line. Defaults to 60 for legacy compatibility.
 
 The `util.inspect()` method returns a string representation of `object` that is
 primarily useful for debugging. Additional `options` may be passed that alter

lib/util.js

@@ -194,6 +194,7 @@ function inspect(obj, opts) {
 if(ctx.colors)ctx.stylize=stylizeWithColor;
 if(ctx.maxArrayLength===undefined)ctx.maxArrayLength=kDefaultMaxLength;
 if(ctx.maxArrayLength===null)ctx.maxArrayLength=Infinity;
+if(ctx.breakLength===undefined)ctx.breakLength=60;
 returnformatValue(ctx,obj,ctx.depth);
 }
 exports.inspect=inspect;
@@ -575,7 +576,7 @@ function formatValue(ctx, value, recurseTimes) {
 
 ctx.seen.pop();
 
-returnreduceToSingleString(output,base,braces);
+returnreduceToSingleString(output,base,braces,ctx.breakLength);
 }
 
 
@@ -807,12 +808,12 @@ function formatProperty(ctx, value, recurseTimes, visibleKeys, key, array) {
 }
 
 
-functionreduceToSingleString(output,base,braces){
+functionreduceToSingleString(output,base,braces,breakLength){
 varlength=output.reduce(function(prev,cur){
 returnprev+cur.replace(/\u001b\[\d\d?m/g,'').length+1;
 },0);
 
-if(length>60){
+if(length>breakLength){
 returnbraces[0]+
 // If the opening "brace" is too large, like in the case of "Set {",
 // we need to force the first item to be on the next line or the

test/parallel/test-util-inspect.js

@@ -709,3 +709,16 @@ checkAlignment(new Map(big_array.map(function(y) { return [y, null]; })));
 constx=newUint8Array(101);
 assert(!/1moreitem/.test(util.inspect(x,{maxArrayLength: Infinity})));
 }
+
+{
+constobj={foo: 'abc',bar: 'xyz'};
+constoneLine=util.inspect(obj,{breakLength: Infinity});
+// Subtract four for the object's two curly braces and two spaces of padding.
+// Add one more to satisfy the strictly greater than condition in the code.
+constbreakpoint=oneLine.length-5;
+consttwoLines=util.inspect(obj,{breakLength: breakpoint});
+
+assert.strictEqual(oneLine,'{ foo: \'abc\', bar: \'xyz\' }');
+assert.strictEqual(oneLine,util.inspect(obj,{breakLength: breakpoint+1}));
+assert.strictEqual(twoLines,'{ foo: \'abc\',\n bar: \'xyz\' }');
+}