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JavaScript Programmer’s Reference See also: Associativity, Bit-field,Bitwise shift left (<<), Bitwise shift left then assign (<<=), Bitwise shift operator, Bitwise shift right and assign (>>=), Bitwise unsigned shift right (>>>), Bitwise unsigned shift right and assign (>>>=), Operator Precedence, Shift operator Cross-references: ECMA 262 edition 2 section 11.7.2 ECMA 262 edition 3 section 11.7.2 Bitwise shift right and assign (>>=) (Operator/assignment) Destructively bitwise rightwards shift the first of two operands. Availability: ECMAScript edition 2 JavaScript 1.0 JScript 1.0 Internet Explorer 3.02 Netscape 2.0 Netscape Enterprise Server 2.0 Opera 3.0 Property/method value type: Number primitive JavaScript syntax: -anOperand1 >>= anOperand2 anOperand1 A value to be shifted and assigned to Argument list: =”c2″>anOperand2 =”c3″>A distance to shift anOperand1 Bitwise shift rightwards the left operand by the number of bits in the right operand and assign the result to the left operand. This is functionally equivalent to the expression: anOperand1 = anOperand1 >> anOperand2; The bitwise shift right operator converts its left operand to a 32 bit integer and moves it rightwards by the number of bits indicated by the right operand. As the value is shifted rightwards, bits that roll out of the right end of the register are discarded. The left-hand end of the register containing the sign bit is duplicated to sign fill the value as it shifts. Shifting rightwards by 32 bits will fill the left operand with all zero or all one bits according to the value of the sign bit at the outset. Because the value is converted to an integer, any fractional part is discarded as the shift begins.

B Bitwise shift right (>>) (Operator/bitwise) 0 1 1 0 1 0 1 0 1 1 0 1 00 1 1 1 0 1 0 1 1 1 1 0 1 01 Example code:

JavaScript Programmer’s Reference Bitwise shift right (>>) (Operator/bitwise) Bitwise shift right one operand according to another. Availability: ECMAScript edition 2 JavaScript 1.0 JScript 1.0 Internet Explorer 3.02 Netscape 2.0 Netscape Enterprise Server 2.0 Opera 3.0 Property/method value type: Number primitive JavaScript syntax: -anOperand1 >> anOperand2 anOperand1 A value to be shifted Argument list: anOperand2 A distance to shift the left operand This is sometimes called shift right with sign extension. The bitwise shift right operator converts its left operand to a 32 bit integer and moves it rightwards by the number of bits indicated by the right operand. As the value is shifted rightwards, bits that roll out of the right end of the register are discarded. The left-hand end of the register containing the sign bit is duplicated to sign-fill the value as it shifts. Shifting rightwards by 32 bits will fill the register with all zero or all one bits according to the value of the sign bit at the outset. Because the value is converted to an integer, any fractional part is discarded as the shift begins. The right-hand operand is converted to a 5-bit value with a bitwise mask to limit the distance of the shift to 32 bits. This can cause unexpected results if the right-hand side is derived from an expression that may yield a value larger than 32. The associativity is left to right. Refer to the Operator Precedence topic for details of execution order. You can accomplish bitwise shift rights by dividing values using powers of 2. Dividing a value by 2 shifts rightwards by one bit position.

B Bitwise shift operator (Definition) The new value of anOperand1 is returned as a result of the expression. 0 1 1 0 1 0 1 01 1 0 1 0 1 Warnings: . The operand to the left of the operator must be an LValue. That is, it should be able to take an assignment and store the value. Assignment operator, Associativity, Bit-field,Bitwise operator, Bitwise shift left (<<), Bitwise shift operator, Bitwise shift right (>>), Bitwise shift right and assign (>>=), Bitwise unsigned shift right (>>>), Bitwise unsigned shift right and assign (>>>=), LValue,Operator Precedence,Shift operator See also: Cross-references: ECMA 262 edition 2 section 11.13 ECMA 262 edition 3 section 11.13 Bitwise shift operator (Definition) A shift operator that moves the bits in an operand as if it were a shift register. Availability: Property/method value type: ECMAScript edition 2 Number primitive Bitwise shift operators convert their left operands to a 32-bit integer value and shift them according to their right operand. The operator determines the kind of shifting that is applied. Bit-field, Bitwise shift left (<<), Bitwise shift left then assign (<<=), Bitwise shift right (>>), Bitwise shift right and assign (>>=), Bitwise unsigned shift right (>>>), Bitwise unsigned shift right and assign (>>>=),Shift expression, Shift operator See also: Cross-references: ECMA 262 edition 2 section 11.7 ECMA 262 edition 3 section 11.7

JavaScript Programmer’s Reference Bitwise shift left then assign (<<=) (Operator/assignment) Destructively bitwise leftwards shift the first of two operands. Availability: ECMAScript edition 2 JavaScript 1.0 JScript 1.0 Internet Explorer 3.02 Netscape 2.0 Netscape Enterprise Server 2.0 Opera browser 3.0 Property/method value type: Number primitive JavaScript syntax: -anOperand1 <<= anOperand2 anOperand1 A value to be shifted and assigned to Argument list: anOperand2 A distance to shift anOperand1 Bitwise shift leftwards the left operand by the number of bits in the right operand and assign the result to the left operand. This is functionally equivalent to the expression: anOperand1 = anOperand1 << anOperand2; The bitwise shift left operator converts it left operand to a 32 bit integer and moves it leftwards by the number of bits indicated by the right operand. As the value is shifted leftwards, bits that roll out of the left end of the register are discarded. The right-hand end of the register is filled with zero bits. Shifting leftwards by 32 bits will fill the left operand with all zero bits. Because the value is converted to an integer, any fractional part is discarded as the shift begins. The right-hand operand is converted to a 5-bit value with a bitwise mask to limit the distance of the shift to 32 bits. This can cause unexpected results if the right-hand side is derived from an expression that may yield a value larger than 32. Although this is classified as an assignment operator it is really a compound of an assignment and a bitwise operator. The associativity is right to left. Refer to the Operator Precedence topic for details of execution order.

B Bitwise shift left (<<) (Operator/bitwise) Example code: See also: Associativity, Bit-field,Bitwise shift left then assign (<<=), Bitwise shift operator, Bitwise shift right (>>), Bitwise shift right and assign (>>=), Bitwise unsigned shift right (>>>), Bitwise unsigned shift right and assign (>>>=), Operator Precedence, Shift operator Cross-references: ECMA 262 edition 2 section 11.7.1 ECMA 262 edition 3 section 11.7.1

JavaScript Programmer’s Reference Bitwise shift left (<<) (Operator/bitwise) Bitwise shift leftwards one operand according to another. Number primitive anOperand1 << anOperand2 A distance to shift anOperand1 The bitwise shift left operator converts its left operand to a 32 bit integer and moves it leftwards by the number of bits indicated by the right operand. Availability: Property/method value type: JavaScript syntax: - Argument list: anOperand1 anOperand2 A value to be shifted As the value is shifted leftwards, bits that roll out of the left end of the register are discarded. The right-hand end of the register is filled with zero bits. Shifting leftwards by 32 bits will fill the register with all zero bits. Because the value is converted to an integer, any fractional part is discarded as the shift begins. The right-hand operand is converted to a 5 bit value with a bitwise mask to limit the distance of the shift to 32 bits. This can cause unexpected results if the right-hand side is derived from an expression that may yield a value larger than 32. The associativity is left to right. Refer to the Operator Precedence topic for details of execution order. You can accomplish bitwise shift lefts by multiplying values using powers of 2. Multiplying a value by 2 shifts leftwards by one bit position. ECMAScript edition 2 JavaScript 1.0 JScript 1.0 Internet Explorer 3.02 Netscape 2.0 Netscape Enterprise Server 2.0 Opera 3.0 0 1 1 0 1 0 1 01 1 0 1 0 1

B Bitwise OR then assign (|=) (Operator/assignment) Bitwise OR the right operand with the left operand and assign the result to the left operand. This is functionally equivalent to the expression: anOperand1 = anOperand1 | anOperand2; Performs a bit by bit OR of the 32-bit value derived from both operands. Where a corresponding bit is 1 in either of the two operands, a 1 is inserted into the result. A zero is inserted only when neither operand has a 1 bit at that position. Although this is classified as an assignment operator it is really a compound of an assignment and a bitwise operator. The associativity is right to left. Refer to the Operator Precedence topic for details of execution order. The new value of anOperand1is returned as a result of the expression. The truth table shows the result of this operator for two Boolean primitive values: A B OR false false false true true false true true false true true true This is applied to each corresponding bit pair in the operands. Warnings: . The operand to the left of the operator must be an LValue. That is, it should be able to take an assignment and store the value. See also: Assignment operator, Associativity, Bit-field, Bitwise operator, Bitwise OR (|),LValue, Operator Precedence Cross-references: ECMA 262 edition 2 section 11.13 ECMA 262 edition 3 section 11.13

JavaScript Programmer’s Reference document.write(”OR : ” + binary32(myValue3) + “
“); // Binary convertor (ignore sign bit on MSIE) function binary32(aValue) { myArray = new Array(32); for(myEnum=0; myEnum<32; myEnum++) { if(aValue & Math.pow(2, myEnum)) { myArray[31-myEnum] = "1"; } else { myArray[31-myEnum] = "0"; } } return myArray.join(""); } See also: Associativity, Binary bitwise operator, Bit-field,Bitwise OR then assign (|=), Operator Precedence Cross-references: ECMA 262 edition 2 section 11.10 ECMA 262 edition 3 section 11.10 Bitwise OR then assign (|=) (Operator/assignment) Bitwise OR two operands and assign the result to the first. Availability: Property/method value type: JavaScript syntax: Argument list: - ECMAScript edition 2 JavaScript 1.0 JScript 1.0 Internet Explorer 3.02 Netscape 2.0 Netscape Enterprise Server 2.0 Opera 3.0 Number primitive -anOperand1 |= anOperand2 anOperand1 A numeric value that can be assigned to anOperand2 Another numeric value

B Bitwise OR (|) (Operator/bitwise) Bitwise OR (|) (Operator/bitwise) Bitwise OR of two operands. ECMAScript edition 2 JavaScript 1.0 JScript 1.0 Internet Explorer 3.02 Netscape 2.0 Netscape Enterprise Server 2.0 Opera 3.0 Number primitive -anOperand1 | anOperand2 anOperand1 A numeric value anOperand2 Another numeric value Availability: Property/method value type: JavaScript syntax: Argument list: - Performs a bit-by-bit OR of the 32-bit value derived from both operands. Where a corresponding bit is 1 in either of the two operands, a 1 is inserted into the result. A zero is inserted only when neither operand has a 1 bit at that position. The associativity is left to right. Refer to the Operator Precedence topic for details of execution order. The truth table shows the result of this operator for two Boolean primitive values: A B OR false false false false true true true false true true true true This is applied to each corresponding bit pair in the operands. Example code: